[libc++abi][CMake] Handle build type RelWithDebInfo or MinSizeRel configuration similarly to Release

[xingxue]

Summary

This patch is similar to the change in libunwind (D124912) to make sure assertions are enabled in the build if LIBCXXABI_ENABLE_ASSERTIONS is set (which it is by default), when building in RelWithDebInfo or MinSizeRel configurations.

[xingxue]

Refreshed the patch with context.

[MaskRay]

[libc++abi][CMake] Handle build type RelWithDebInfo configuration similarly to Release

Mention MINSIZEREL as well.

From reading https://github.com/Kitware/CMake/blob/master/Modules/Compiler/GNU.cmake#L58 , I think this makes sense.

[xingxue]

In D136770#3886558, @MaskRay wrote:

[libc++abi][CMake] Handle build type RelWithDebInfo configuration similarly to Release

Mention MINSIZEREL as well.

From reading https://github.com/Kitware/CMake/blob/master/Modules/Compiler/GNU.cmake#L58 , I think this makes sense.

Changed to mention MinSizeRel as well, thanks!

[xingxue]

@ldionne, can you please take a look for #libc_abi? Thanks!

[xingxue]

Gentle ping...

libcxxabi/CMakeLists.txt

 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 if (LIBCXXABI_ENABLE_ASSERTIONS)
   # MSVC doesn't like _DEBUG on release builds. See PR 4379.
   if (NOT MSVC)
     list(APPEND LIBCXXABI_COMPILE_FLAGS -D_DEBUG)
   endif()
   # On Release builds cmake automatically defines NDEBUG, so we
   # explicitly undefine it:
-  if (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
+  if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
     list(APPEND LIBCXXABI_COMPILE_FLAGS -UNDEBUG)
   endif()
 else()
-  if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
+  if (uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
     list(APPEND LIBCXXABI_COMPILE_FLAGS -DNDEBUG)
   endif()
 endif()
 
 # Threading
 if (NOT LIBCXXABI_ENABLE_THREADS)
   if (LIBCXXABI_HAS_PTHREAD_API)
     message(FATAL_ERROR "LIBCXXABI_HAS_PTHREAD_API can only"