[ms-inline asm] The parsing of C++ identifiers is a task of the front-end parser,
not the asm parser.  As such, begin moving the parsing logic in that direction.
This patch is just a temporary hack until the real frontend parser can be hooked
up.  Part of rdar://13663589

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179882 91177308-0d34-0410-b5e6-96231b3b80d8