Lex: Don't let annotation tokens get into macro expansion

We'd let annotation tokens from '#pragma pack' and the like get inside a
function-like macro.  This would lead to terror and mayhem; stop the
madness early.

This fixes PR22037.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@224896 91177308-0d34-0410-b5e6-96231b3b80d8