Revert "Reland r206934 with a hopefully fixed test"

This reverts commit r207155.
The test was still failing.

llvm-svn: 207225
diff --git a/clang/lib/Driver/WindowsToolChain.cpp b/clang/lib/Driver/WindowsToolChain.cpp
index aba06d6..cd6d7e1 100644
--- a/clang/lib/Driver/WindowsToolChain.cpp
+++ b/clang/lib/Driver/WindowsToolChain.cpp
@@ -293,6 +293,7 @@
   if (DriverArgs.hasArg(options::OPT_nostdlibinc))
     return;
 
+#ifdef _MSC_VER
   // Honor %INCLUDE%. It should know essential search paths with vcvarsall.bat.
   if (const char *cl_include_dir = getenv("INCLUDE")) {
     SmallVector<StringRef, 8> Dirs;
@@ -304,7 +305,6 @@
       return;
   }
 
-#ifdef _MSC_VER
   std::string VSDir;
   std::string WindowsSDKDir;