avplay: Exit by default at the end of playback

This is the expected behavior shared by all other cli multimedia players.

Bug-Id: 732
Merge commit '041caf1a63f091745b95a6d51c23fbdcb604d4ce'

* commit '041caf1a63f091745b95a6d51c23fbdcb604d4ce':
  avplay: Exit by default at the end of playback

Conflicts:
	Changelog
	ffplay.c

Changes to ffplay not merged as they would break -autoexit as a way to override -noautoexit,
the change of the default will be implemented in the next commit

Merged-by: Michael Niedermayer <michaelni@gmx.at>
ffplay: make autoexit the default

See: f9bc65e399d1883da21ae03d07b09348a11a5f49
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>