[MSVC Compat] Fix typo correction for inclusion directives.

In MSVC compatibility mode we were checking not the typo corrected
filename but the original filename.

Reviewers: christylee, compnerd

Reviewed By: christylee

Subscribers: jkorous, dexonsmith, sammccall, hokein, cfe-commits

Differential Revision: https://reviews.llvm.org/D56631

llvm-svn: 351232