Fix a little crasher in friend decls.  Thanks again to Eli for finding this.

llvm-svn: 80748
diff --git a/clang/lib/Sema/Sema.h b/clang/lib/Sema/Sema.h
index 63d2831..e2205d6 100644
--- a/clang/lib/Sema/Sema.h
+++ b/clang/lib/Sema/Sema.h
@@ -715,10 +715,11 @@
   /// Finds the scope corresponding to the given decl context, if it
   /// happens to be an enclosing scope.  Otherwise return NULL.
   Scope *getScopeForDeclContext(Scope *S, DeclContext *DC) {
-    DC = DC->getPrimaryContext();
+    DeclContext *TargetDC = DC->getPrimaryContext();
     do {
-      if (((DeclContext*) S->getEntity())->getPrimaryContext() == DC)
-        return S;
+      if (DeclContext *ScopeDC = (DeclContext*) S->getEntity())
+        if (ScopeDC->getPrimaryContext() == TargetDC)
+          return S;
     } while ((S = S->getParent()));
 
     return NULL;