cmake HAVE_LIBCXXABI examples

trailofbits/polytracker polytracker/src/compiler-rt/CMakeLists.txt :473 

elseif (TARGET cxxabi_shared OR HAVE_LIBCXXABI)

PlatONnetwork/pWASM libc++/libcxx/CMakeLists.txt :127 

elseif ((NOT LIBCXX_STANDALONE_BUILD OR HAVE_LIBCXXABI) AND
          IS_DIRECTORY "${LIBCXX_LIBCXXABI_INCLUDES_INTERNAL}")