Before this patch, passing a non-existent absolute path to clang-cl would cause
stat'ing of impossible paths. For example, `clang-cl -c d:\adsfasdf.txt` would
cause a stat of
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\LIBd:\asdfadsf.cc
llvm-svn: 235787
Test Plan: The patch includes a test case.
Reviewers: hansw
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5338
llvm-svn: 217710
These are used to specify source files, and whether to treat source
files as C or C++.
Differential Revision: http://llvm-reviews.chandlerc.com/D1290
llvm-svn: 187760