Remove PathV1.h use from WindowsToolChain.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184906 91177308-0d34-0410-b5e6-96231b3b80d8
Remove some uses of llvm::sys::Path.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184907 91177308-0d34-0410-b5e6-96231b3b80d8