Driver support for -fdebug-types-sections

Using backend-option like a few other debug codegen flags. I believe
Eric Christopher's working at porting those over to something nicer
such as an API level CodeGenOptions or the like, so this can be
improved along with that work.

llvm-svn: 199535
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index cb65fc8..92f35f3 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2599,7 +2599,10 @@
     CmdArgs.push_back("-generate-gnu-dwarf-pub-sections");
   }
 
-  Args.AddAllArgs(CmdArgs, options::OPT_fdebug_types_section);
+  if (Args.hasArg(options::OPT_fdebug_types_section)) {
+    CmdArgs.push_back("-backend-option");
+    CmdArgs.push_back("-generate-type-units");
+  }
 
   Args.AddAllArgs(CmdArgs, options::OPT_ffunction_sections);
   Args.AddAllArgs(CmdArgs, options::OPT_fdata_sections);