supporting other targets. Changed the code to pass MCAsmInfo to the parser
and the lexer. Then changed the lexer to use CommentString from MCAsmInfo
instead of a literal '#' character.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81046 91177308-0d34-0410-b5e6-96231b3b80d8