Add support for the /Fi argument to clang-cl (PR20036)

Patch by Ehsan Akhgari!

Differential Revision: http://reviews.llvm.org/D4143

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211081 91177308-0d34-0410-b5e6-96231b3b80d8