Add methods to remove a GDM entry.
Instead of setting the ReturnExpr GDM to NULL, remove it.

llvm-svn: 99470
diff --git a/clang/lib/Checker/GRState.cpp b/clang/lib/Checker/GRState.cpp
index 2defbcd..f2952bc 100644
--- a/clang/lib/Checker/GRState.cpp
+++ b/clang/lib/Checker/GRState.cpp
@@ -227,6 +227,18 @@
   return getPersistentState(NewSt);
 }
 
+const GRState *GRStateManager::removeGDM(const GRState *state, void *Key) {
+  GRState::GenericDataMap OldM = state->getGDM();
+  GRState::GenericDataMap NewM = GDMFactory.Remove(OldM, Key);
+
+  if (NewM == OldM)
+    return state;
+
+  GRState NewState = *state;
+  NewState.GDM = NewM;
+  return getPersistentState(NewState);
+}
+
 //===----------------------------------------------------------------------===//
 // Utility.
 //===----------------------------------------------------------------------===//