Fix the "git modified" issue on the preserve-comments-crlf.s.

Summary:
 rL371473 corrected the line ending (to crlf) in preserve-comments-crlf.s, but it causes a wired issue on git
 repository (I ran git pull today, it showed a local change of that file even I did not change anything).

Reviewers: gribozavr

Reviewed By: gribozavr

Subscribers: llvm-commits, cfe-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67391

llvm-svn: 371513