CodeGen: Don't try to canonicalize Unix-style paths in CodeView debug info.

Most importantly, we should not replace slashes with backslashes
because that would invalidate the path.

Differential Revision: https://reviews.llvm.org/D45473

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@329838 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed