[clang] disable P2266 simpler implicit moves under -fms-compatibility

The Microsoft STL currently has some issues with P2266.
We disable it for now in that mode, but we might come back later with a
more targetted approach.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D105518