(LLVM part) Implement MASM-flavor intel syntax behavior for inline MS asm block:

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: 280555