When we decide to output a deferred decl, remember the llvm GlobalValue.

We can reuse it to avoid a DenseMap+StringMap lookup to find if it was already
emitted or not.

This fixes a 2010 TODO.

llvm-svn: 196785

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -117,6 +117,8 @@ namespace {
 
     virtual void HandleTranslationUnit(ASTContext &Ctx) {
       if (Diags.hasErrorOccurred()) {
+        if (Builder)
+          Builder->clear();
         M.reset();
         return;
       }