clang-cl: pass /FI options to fallback

We started parsing /FI in r191442, and now we can pass it on to the
fallback too.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191537 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 6edb447..cb28cd1 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -6733,6 +6733,10 @@
   if (Args.hasArg(options::OPT_fsyntax_only))
     CmdArgs.push_back("/Zs");
 
+  std::vector<std::string> Includes = Args.getAllArgValues(options::OPT_include);
+  for (size_t I = 0, E = Includes.size(); I != E; ++I)
+    CmdArgs.push_back(Args.MakeArgString(std::string("/FI") + Includes[I]));
+
   // Flags that can simply be passed through.
   Args.AddAllArgs(CmdArgs, options::OPT__SLASH_LD);
   Args.AddAllArgs(CmdArgs, options::OPT__SLASH_LDd);