[X86][MS-compatability][clang] allow MS TYPE/SIZE/LENGTH operators as a part of a...

[X86][MS-compatability][clang] allow MS TYPE/SIZE/LENGTH operators as a part of a compound expression

This patch introduces X86AsmParser with the ability to handle the aforementioned ops within compound "MS" arithmetical expressions.
Currently - only supported as a stand alone Operand, e.g.:
"TYPE X"
now allowed :
"4 + TYPE X * 128"

LLVM side: https://reviews.llvm.org/D31173
Differential Revision: https://reviews.llvm.org/D31174

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298426 91177308-0d34-0410-b5e6-96231b3b80d8