[NFC] Header cleanup

Summary: Removed unused headers, replaced some headers with forward class declarations

Patch by: Eugene <claprix@yandex.ru>

Differential Revision: https://reviews.llvm.org/D20100

llvm-svn: 275882
diff --git a/clang/lib/Driver/MSVCToolChain.cpp b/clang/lib/Driver/MSVCToolChain.cpp
index b8de5ad..64323c4 100644
--- a/clang/lib/Driver/MSVCToolChain.cpp
+++ b/clang/lib/Driver/MSVCToolChain.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include <cstdio>