Capture CMAKE_<LANG>_COMPILER_ARG1 from CMAKE_<LANG>_COMPILER in the
same fashion that it is from $ENV{<LANG>}.
Since get_filename_component() returns a single string of all the
arguments from $ENV{<LANG>}, a single string of arguments will be
constructed from the items contained in CMAKE_<LANG>_COMPILER.
Fixes#20089
Add entries in Modules and Modules/Platform to support
Objective-C++ compiler determination and identification.
Add Modules to check Objective-C++ compiler flags, source
compilations, program checks, etc...
Use OBJCXX as the designator of the language, eg:
project(foo OBJCXX)
Add various tests for Objective-C++ language features. Add
tests to preserve C++ handling of .M and .mm files when
Objective-C++ is not a configured language.
Co-authored-by: Cristian Adam <cristian.adam@gmail.com>
Fred Baksik