fix formatting.
Do not reuse the debug location of the return value's store if there is autorelease code to be emitted between store and return instructions. This is analoguous to what we do for lexical scope cleanups.

rdar://problem/13977888
[analyzer] Don't crash if a block's signature just has the return type.

It is okay to declare a block without an argument list: ^ {} or ^void {}.
In these cases, the BlockDecl's signature-as-written will just contain
the return type, rather than the entire function type. It is unclear if
this is intentional, but the analyzer shouldn't crash because of it.

<rdar://problem/14018351>