[lldb] Correct documentation of LLDB_TEST_USER_ARGS (#89042)

https://discourse.llvm.org/t/running-lldb-in-a-container/76801/4 found
that the obvious way to use this variable doesn't work, despite what our
docs and examples say.

Perhaps in the past it did but now you need to use ";" as a separator to
make sure the final command line works properly.

For example "-A foo" becomes "-A foo" when python goes to run the runner
script. The script sees this as one command line element, not two. What
you actually want is "-A;foo" which we convert to "-A" "foo" which the
script sees as one option and one value for that option.

The "Script:" printout from dotest is misleading here because it does `"
".join(cmd)` so it looks like it's ok but in fact it's not.

I'm not changing that format though because printing the command as a
Python list is not useful outside of this specific situation.

Author: DavidSpickett

lldb/docs/resources/test.rst

@@ -441,23 +441,40 @@ Running the Full Test Suite
 The easiest way to run the LLDB test suite is to use the ``check-lldb`` build
 target.
 
+::
+
+   $ ninja check-lldb
+
+Changing Test Suite Options
+```````````````````````````
+
 By default, the ``check-lldb`` target builds the test programs with the same
 compiler that was used to build LLDB. To build the tests with a different
 compiler, you can set the ``LLDB_TEST_COMPILER`` CMake variable.
 
+You can also add to the test runner options by setting the
+``LLDB_TEST_USER_ARGS`` CMake variable. This variable uses ``;`` to separate
+items which must be separate parts of the runner's command line.
+
 It is possible to customize the architecture of the test binaries and compiler
-used by appending ``-A`` and ``-C`` options respectively to the CMake variable
-``LLDB_TEST_USER_ARGS``. For example, to test LLDB against 32-bit binaries
-built with a custom version of clang, do:
+used by appending ``-A`` and ``-C`` options respectively. For example, to test
+LLDB against 32-bit binaries built with a custom version of clang, do:
 
 ::
 
-   $ cmake -DLLDB_TEST_USER_ARGS="-A i386 -C /path/to/custom/clang" -G Ninja
+   $ cmake -DLLDB_TEST_USER_ARGS="-A;i386;-C;/path/to/custom/clang" -G Ninja
    $ ninja check-lldb
 
 Note that multiple ``-A`` and ``-C`` flags can be specified to
 ``LLDB_TEST_USER_ARGS``.
 
+If you want to change the LLDB settings that tests run with then you can set
+the ``--setting`` option of the test runner via this same variable. For example
+``--setting;target.disable-aslr=true``.
+
+For a full list of test runner options, see
+``<build-dir>/bin/lldb-dotest --help``.
+
 Running a Single Test Suite
 ```````````````````````````
 

lldb/test/API/CMakeLists.txt

@@ -35,7 +35,8 @@ set(LLDB_TEST_ARCH
 # Users can override LLDB_TEST_USER_ARGS to specify arbitrary arguments to pass to the script
 set(LLDB_TEST_USER_ARGS
   ""
-  CACHE STRING "Specify additional arguments to pass to test runner. For example: '-C gcc -C clang -A i386 -A x86_64'")
+  CACHE STRING "Specify additional arguments to pass to test runner. Seperate \
+items with \";\". For example: '-C;gcc;-C;clang;-A;i386;-A;x86_64'")
 
 set(LLDB_TEST_COMMON_ARGS_VAR
   -u CXXFLAGS