MS inline asm: When LLVM called back to Clang to parse a name and do name

MS inline asm: When LLVM called back to Clang to parse a name and do name
lookup, if parsing failed, we did not restore the lexer state properly, and
eventually crashed.  This change ensures that we always consume all the tokens
from the new token stream we started to parse the name from inline asm.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196182 91177308-0d34-0410-b5e6-96231b3b80d8