[silgen] Add a new private API on CleanupManager called isFormalAccessCleanup.

I am going to use this in ManagedValue.

Author: gottesmm

lib/SILGen/Cleanup.cpp

@@ -220,6 +220,12 @@ void CleanupManager::setCleanupState(CleanupsDepth depth, CleanupState state) {
     popTopDeadCleanups();
 }
 
+bool CleanupManager::isFormalAccessCleanup(CleanupHandle depth) {
+  using RawTy = std::underlying_type<Cleanup::Flags>::type;
+  auto state = getFlagsAndWritebackBuffer(depth);
+  return RawTy(std::get<0>(state)) & RawTy(Cleanup::Flags::FormalAccessCleanup);
+}
+
 std::tuple<Cleanup::Flags, llvm::Optional<SILValue>>
 CleanupManager::getFlagsAndWritebackBuffer(CleanupHandle depth) {
   auto iter = stack.find(depth);

lib/SILGen/Cleanup.h

@@ -294,6 +294,8 @@ class LLVM_LIBRARY_VISIBILITY CleanupManager {
   // cleanup at \p depth. If
   std::tuple<Cleanup::Flags, llvm::Optional<SILValue>>
   getFlagsAndWritebackBuffer(CleanupHandle depth);
+
+  bool isFormalAccessCleanup(CleanupHandle depth);
 };
 
 /// An RAII object that allows the state of a cleanup to be