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

(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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280556 91177308-0d34-0410-b5e6-96231b3b80d8