Partially revert "[cmake] Make MSVC generate appropriate __cplusplus macro definition"

The /Zc:__cplusplus option fixes GTEST_LANG_CXX11 value but not GTEST_HAS_TR1_TUPLE,
so we still need to force the latter off.

Still pass the option since it is required by https://reviews.llvm.org/D78186 too.

Differential Revision: https://reviews.llvm.org/D84023