Revert r277408 and r277407

Revert r277408 "Fix test from rL277407."
Revert r277407 "[MC] Fix handling of end-of-line preprocessor comments"

This is currently breaking:
  http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA_check/20731

llvm-svn: 277412