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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371513 91177308-0d34-0410-b5e6-96231b3b80d8

.gitattributes

@@ -13,5 +13,7 @@ test/tools/llvm-strings/Inputs/numbers binary
 test/MC/AsmParser/incbin_abcd binary
 test/YAMLParser/spec-09-02.test binary
 
-# Windows line ending test
-test/MC/AsmParser/preserve-comments-crlf.s text eol=crlf
+# This file must have CRLF line endings, therefore git should treat it as
+# binary and not autoconvert line endings (for example, when core.autocrlf is
+# on).
+test/MC/AsmParser/preserve-comments-crlf.s binary