[X86] Add support for "xlat m8"

According to x86 spec "xlat m8" is a legal instruction and it is equivalent to "xlatb".

Differential Revision: http://reviews.llvm.org/D15150



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258135 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed