Big-endian version of vpermxor

A big-endian version of vpermxor, named vpermxor_be, is added to LLVM
and Clang. vpermxor_be can be called directly on both the little-endian
and the big-endian platforms.

Reviewed By: nemanjai

Differential Revision: https://reviews.llvm.org/D114540

GitOrigin-RevId: 0850655da69a700b7def4fe8d9a44d1c8d55877c
2 files changed