x86: use raw opcode for xgetbv instruction
This allows the CPU detection to work with assemblers not supporting
the xgetbv mnemonic. These include clang and some BSD versions.
All AVX code will be written for yasm, where the main assembler
is not involved.
Signed-off-by: Mans Rullgard <email@example.com>
(cherry picked from commit ef6695387522fc783105ac187c84beaa284e7cff)