Move the closure specializer over to using the new call graph.

Swift SVN r21568

lib/SILPasses/ClosureSpecializer.cpp

@@ -364,7 +364,7 @@ public:
 
     bool Changed = false;
     // Specialize going bottom-up in the call graph.
-    for (auto *F : CGA->bottomUpCallGraphOrder()) {
+    for (auto *F : CGA->getCallGraph().getBottomUpFunctionOrder()) {
       // If F is empty, attempt to link it. Skip it if we fail to do so.
       if (F->empty() &&
           !getModule()->linkFunction(F, SILModule::LinkingMode::LinkAll))