Fix leaks from device monitor and providers
This fixes leaks such that running valgrind
on gst-device-monitor-1.0 -i
no longer returns any valid issues, at least for the providers that are available to me.
Do note that ALSA holds a cache of information, so you need to call snd_config_update_free_global
at the end of real_main
to not flood the output with a bunch of leaks from the cache. I didn't commit that of course, but keep that in mind if you're on a system with ALSA and want to test this out.