clang-cl: /fallback only applies to C or C++ files

We would previously hit an assert if using /fallback with an .ll file.

llvm-svn: 207234
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 924e040..991fe43 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -4066,7 +4066,8 @@
 
   // Finally add the compile command to the compilation.
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
-      Output.getType() == types::TY_Object) {
+      Output.getType() == types::TY_Object &&
+      (InputType == types::TY_C || InputType == types::TY_CXX)) {
     tools::visualstudio::Compile CL(getToolChain());
     Command *CLCommand = CL.GetCommand(C, JA, Output, Inputs, Args,
                                        LinkingOutput);