[X86][MS-compatability]Allow named synonymous for MS-assembly operators

This patch enhances X86AsmParser's immediate expression parsing abilities, to include a named synonymous for selected binary/unary bitwise operators: {and,shl,shr,or,xor,not}, ultimately achieving better MS-compatability
MASM reference:
https://msdn.microsoft.com/en-us/library/94b6khh4.aspx

Differential Revision: D31277

llvm-svn: 299439