Fix leak of dispatch queues during setup. We don’t need to retain the queue after calling dispatch_queue_create because it already has a retain count of 1.
Fix some leaks when using / changing video filters.

Also, we don’t need to check for null before calling free. From the C standard, "If ptr is a null pointer, no action occurs".
Only create an NSXPCConnection if we have a listener endpoint. Calling initWithListenerEndpoint: and passing it nil results in a memory leak.

Update of pull request #1125 with feedback from Clobber.
https://github.com/OpenEmu/OpenEmu/pull/1125
Merge pull request #1125 from sutrobear/bugfix_leaks

Fix some memory leaks.