[libunwind] Introduce LIBUNWIND_LIBRARY_VERSION and drop outdated Apple flags (#110178)

This patch introduces the LIBUNWIND_LIBRARY_VERSION setting to control
the dylib version of libunwind. This allows expressing the dylib version
in CMake instead of adding custom compiler flags.

As a drive-by, also remove some outdated Apple flags that are not
relevant anymore.

Author: ldionne

libunwind/CMakeLists.txt

@@ -61,6 +61,12 @@ cmake_dependent_option(LIBUNWIND_INSTALL_SHARED_LIBRARY
   "Install the shared libunwind library." ON
   "LIBUNWIND_ENABLE_SHARED;LIBUNWIND_INSTALL_LIBRARY" OFF)
 
+set(LIBUNWIND_LIBRARY_VERSION "1.0" CACHE STRING
+  "Version of libunwind. This will be reflected in the name of the shared library produced.
+   For example, -DLIBUNWIND_LIBRARY_VERSION=x.y will result in the library being named
+   libunwind.x.y.dylib, along with the usual symlinks pointing to that. On Apple platforms,
+   this also controls the linker's 'current_version' property.")
+
 if(MINGW)
   set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-mingw.cfg.in")
 elseif (LIBUNWIND_ENABLE_SHARED)

libunwind/src/CMakeLists.txt

@@ -105,15 +105,6 @@ if (LIBUNWIND_ENABLE_SHARED AND
           "on C++ ABI library is not supported.")
 endif()
 
-if (APPLE)
-  add_compile_flags("-U__STRICT_ANSI__")
-  add_link_flags("-compatibility_version 1" "-install_name /usr/lib/libunwind.1.dylib")
-
-  if (CMAKE_OSX_DEPLOYMENT_TARGET STREQUAL "10.6")
-    add_link_flags("-current_version ${LIBUNWIND_VERSION}" "/usr/lib/libSystem.B.dylib")
-  endif ()
-endif ()
-
 if (HAIKU)
   add_library_flags_if(LIBUNWIND_HAS_ROOT_LIB root)
 
@@ -170,8 +161,8 @@ if (LIBUNWIND_ENABLE_SHARED)
       LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}"
       LINKER_LANGUAGE C
       OUTPUT_NAME "${LIBUNWIND_SHARED_OUTPUT_NAME}"
-      VERSION "1.0"
-      SOVERSION "1"
+      VERSION     "${LIBUNWIND_LIBRARY_VERSION}"
+      SOVERSION   "1"
   )
 
   list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_shared")