[scudo] Check if we use __clang_major__ >= 12

This makes sure we have support for MTE instructions.
Later the check can be extended to support MTE on other compilers.

Reviewed By: pcc

Differential Revision: https://reviews.llvm.org/D105722

GitOrigin-RevId: db4c25822a1d9458f961eeb6cecf8a7bbce05b13
1 file changed