Driver: Restore proper naming of crashdump files

Based on a review of r211411 by Jordan Rose.

llvm-svn: 211572
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 4698999..d4c0313 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1303,7 +1303,8 @@
     } else {
       OutputTy = Input->getType();
       if (!Args.hasFlag(options::OPT_frewrite_includes,
-                        options::OPT_fno_rewrite_includes, false))
+                        options::OPT_fno_rewrite_includes, false) &&
+          !CCGenDiagnostics)
         OutputTy = types::getPreprocessedType(OutputTy);
       assert(OutputTy != types::TY_INVALID &&
              "Cannot preprocess this input type!");