Simplify nil-checking in arc.mm:setObjectHasWeakRefs()

[cmpwi]

Line 779 in setObjectHasWeakRefs() performs the following check:

if (obj && cls && objc_test_class_flag(cls, objc_class_flag_fast_arc))

Immediately below on line 782, obj is tested again:

if (obj)

In between the two checks, obj is not modified in any (observable) way. The surrounding body looks like this:

static BOOL setObjectHasWeakRefs(id obj)
{
	BOOL isGlobalObject = isPersistentObject(obj);
	Class cls = isGlobalObject ? Nil : obj->isa;
	if (obj && cls && objc_test_class_flag(cls, objc_class_flag_fast_arc))
	{
		uintptr_t *refCount = ((uintptr_t*)obj) - 1;
		if (obj)
		{
			<...>

Would it make sense to remove the second seemingly unnecessary check for obj? Stylistically, this would also remove one indentation level, which is (in my opinion) also desirable.

[davidchisnall]

Yes, that would be an improvement.

[cmpwi]

And, done.