Alternative handling of comments adjacent to preprocessor directives.

Summary: Store comments in ScopedLineState

Reviewers: klimek, djasper

Reviewed By: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D609

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178537 91177308-0d34-0410-b5e6-96231b3b80d8