bpo-39160 Align the verbs, grammar and defaults for ./configure --help

[tonybaloney]

Updated version based on principles:

• Should not specify --with(out)-xyz in help string, it's implied by default
• Sentences should start with lowercase (as autoconf generates the builtin string with lower case)
• --with-xyx=VALUE will be described as "overriding"
• --with-xyz will be described as "enabling" said feature
• Mac flags should have the same descriptions as what is in Mac/README.rst
• Default value should be in brackets (if known)
• Enumerated options should be shown as =VAL1|VAL2 or [=VAL1|VAL2] if optional

 Optional Features:
  --disable-option-checking  ignore unrecognized --enable/--with options
  --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
  --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
  --enable-universalsdk[=SDKDIR]
                          create a universal binary build. SDKDIR specifies
                          which macOS SDK should be used to perform the build,
                          see Mac/README.rst. (default is no)
  --enable-framework[=INSTALLDIR]
                          create a Python.framework rather than a traditional
                          Unix install. optional INSTALLDIR specifies the
                          installation path. see Mac/README.rst (default is
                          no)
  --enable-shared         enable building a shared Python library (default is
                          no)
  --enable-profiling      enable C-level code profiling with gprof (default is
                          no)
  --enable-optimizations  enable expensive, stable optimizations (PGO, etc.)
                          (default is no)
  --enable-loadable-sqlite-extensions
                          support loadable extensions in _sqlite module, see
                          Doc/library/sqlite3.rst (default is no)
  --enable-ipv6           enable ipv6 (with ipv4) support, see
                          Doc/library/socket.rst (default is yes if supported)
  --enable-big-digits[=15|30]
                          use big digits (30 or 15 bits) for Python longs
                          (default is no)]

 Optional Packages:
  --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
  --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
  --with-universal-archs=ARCH
                          specify the kind of universal binary that should be
                          created. this option is only valid when
                          --enable-universalsdk is set; options are:
                          ("32-bit", "64-bit", "3-way", "intel", "intel-32",
                          "intel-64", or "all") see Mac/README.rst
  --with-framework-name=FRAMEWORK
                          specify the name for the python framework on macOS
                          only valid when --enable-framework is set. see
                          Mac/README.rst (default is 'Python')
  --with-cxx-main[=COMPILER]
                          compile main() and link Python executable with C++
                          compiler specified in COMPILER (default is $CXX)
  --with-suffix=SUFFIX    set executable suffix to SUFFIX (default is '.exe')
  --with-pydebug          build with Py_DEBUG defined (default is no)
  --with-trace-refs       enable tracing references for debugging purpose
                          (default is no)
  --with-assertions       build with C assertions enabled (default is no)
  --with-lto              enable Link-Time-Optimization in any build (default
                          is no)
  --with-hash-algorithm=[fnv|siphash24]
                          select hash algorithm for use in Python/pyhash.c
                          (default is SipHash24)
  --with-address-sanitizer
                          enable AddressSanitizer memory allocation
                          controller, 'asan' (default is no)
  --with-memory-sanitizer enable MemorySanitizer memory allocation controller,
                          'msan' (default is no)
  --with-undefined-behavior-sanitizer
                          enable UndefinedBehaviorSanitizer memory allocation
                          controller, 'ubsan' (default is no)
  --with-libs='lib1 ...'  link against additional libs (default is no)
  --with-system-expat     build pyexpat module using an installed system expat
                          library, see Doc/library/pyexpat.rst (default is no)
  --with-system-ffi       build _ctypes module using an installed ffi library,
                          see Doc/library/ctypes.rst (default is system
                          dependant)
  --with-system-libmpdec  build _decimal module using an installed libmpdec
                          library, see Doc/library/decimal.rst (default is no)
  --with-tcltk-includes='-I...'
                          override search for Tcl and Tk include files
  --with-tcltk-libs='-L...'
                          override search for Tcl and Tk libs
  --with-dbmliborder=db1:db2:...
                          override order to check db backends for dbm. valid
                          value is a colon separated string with the backend
                          names `ndbm', `gdbm' and `bdb'.
  --with-doc-strings      enable documentation strings (default is yes)
  --with-pymalloc         enable specialized mallocs (default is yes)
  --with-c-locale-coercion
                          enable C locale coercion to a UTF-8 based locale
                          (default is yes)
  --with-valgrind         enable Valgrind support (default is no)
  --with-dtrace           enable DTrace support (default is no)
  --with-libm=STRING      override libm math library to STRING (default is
                          system dependant)
  --with-libc=STRING      override libc C library to STRING (default is system
                          dependant)
  --with-computed-gotos   enable computed gotos in evaluation loop (enabled by
                          default on supported compilers)
  --with-ensurepip[=install|upgrade|no]
                          "install" or "upgrade" using bundled pip (default is
                          upgrade)
  --with-openssl=DIR      override root of the OpenSSL directory to DIR
  --with-ssl-default-suites=[python|openssl|STRING]
                          override default cipher suites string, python: use
                          Python's preferred selection (default), openssl:
                          leave OpenSSL's defaults untouched, STRING: use a
                          custom string, PROTOCOL_SSLv2 ignores the setting,
                          see Doc/library/ssl.rst

https://bugs.python.org/issue39160

[tonybaloney]

Also requesting review from @Yhg1s (if the expert index is up to date). Although this doesn't change any behaviours in autoconf

[tonybaloney]

As a follow on. This needs more documentation somewhere, it's only referenced in the release notes

[tonybaloney]

I think the dtrace support also needs documenting somewhere, it's a really useful feature when you know how to use it. It's not mentioned in the profiling section of docs

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[tonybaloney]

I have made the requested changes; please review again

[bedevere-bot]

Thanks for making the requested changes!

@Yhg1s: please review the changes made to this pull request.

[Yhg1s]

@ned-deily should review the framework help strings, since I don't know much about that.

[Yhg1s]

This is a little misleading: the default is not to link with CXX at all, although the default value when passing --with-cxx-main is indeed CXX. (As an aside, I don't think this option is useful anymore; I believe it was only necessary with gcc 2.95, perhaps only on some platforms.)

[tonybaloney]

thanks, @Yhg1s, the framework help strings are copied from mac/README

[ned-deily]

Looks good to me. It's a nice improvement, thanks! I'm going to merge the PR as it stands. If you want to follow up on the suggestions for additional changes, let's open another PR for that.