(clang part) Implement MASM-flavor intel syntax behavior for inline MS asm block.

Clang tests for verifying the following syntaxes:
1. 0xNN and NNh are accepted as valid hexadecimal numbers, but 0xNNh is not.     
   0xNN and NNh may come with optional U or L suffix.                            
2. NNb is accepted as a valid binary (base-2) number, but 0bNN is not.           
   NNb may come with optional U or L suffix.                                     
                                                                                 
Differential Revision: https://reviews.llvm.org/D22112

llvm-svn: 280556