SILGen: Remaining fixes for @callee_guaranteed closures and enable it

- Fix block to func reabstraction thunks block argument handling
- Forward cast ownership
- Fix applyPartiallyAppliedSuperMethod ownership for @callee_guaranteed closures
- Avoid a copy in buildBlockToFuncThunkBody
- Update tests for callee_guaranteed closures

SR-5441
rdar://33255593

include/swift/AST/SILOptions.h

@@ -115,7 +115,7 @@ public:
   
   /// Emit captures and function contexts using +0 caller-guaranteed ARC
   /// conventions.
-  bool EnableGuaranteedClosureContexts = false;
+  bool EnableGuaranteedClosureContexts = true;
 
   /// Don't generate code using partial_apply in SIL generation.
   bool DisableSILPartialApply = false;