Workaround bug in GCC 7.2
Workaround bug in GCC 7.2

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83830.
Before GCC 7.4, __cpp_lib_has_unique_object_representations was defined
but has_unique_object_representations_v was not.

abseil/abseil-cpp,abseil/abseil-cpp,abseil/abseil-cpp,abseil/abseil-cpp