Removed distinction between "available" and "init" in audio backends, since both had to be checked for success as a pair at the higher level and several of the Available methods were just always-succeed placeholders anyhow. Now the availability check is done in the init code, and the higher level tries all possible drivers until one manages to initialize successfully.

The test programs in this directory tree are for demonstrating and
testing the functionality of the SDL library, and are placed in the
public domain.

October 28, 1997
--
	Sam Lantinga				(slouken@libsdl.org)