Crash when setting self.currentTIme

[Sandoze]

OALAudioTrack.m:799 self.currentTime = 0 will result in a crash.

Steps to reproduce:

1. Begin playing OALAudioTrack(s)
2. Clear track(s)
3. crash

 if(player)
      player.currentTime = currentTime;     <---- player is no longer valid 

Tested on 3.2

[kstenerud]

Posted a bugfix and the problem went away on my end. Please close the ticket if the latest codebase works for you.

[Sandoze]

fixed