The data produced by the callback is just thrown away and the audio thread
delays as if it's waiting for the hardware to drain.
This lets apps that rely on their audio callback firing regularly continue
to make progress to function as properly as possible in the face of disaster.
Apps that want to know that the device is really gone and deal with that
scenario can use the new hotplug functionality.
Device enumeration now happens at startup and then is managed exclusively
through hotplugging instead of full redetection. The device name list now has
a unique "handle" associated with each item and SDL will pass this to the
backend so they don't have to figure out how a human readable name maps to
real hardware for a second time.
Other cleanups, fixes, improvements, plus all the audio backends updated to
the new interface...largely untested at this point, though.
This fills in the core pieces and fully implements it for Mac OS X.
Most other platforms, at the moment, will report a disconnected device if
it fails to write audio, but don't notice if the system's device list changed
at all.
Jonas Kulla
The configure script didn't differentiate between Linux and Android, unconditionally compiling in the unix implementation of SDL_sysfilesystem.c.
I'm probably one of the very few people building SDL for android using classic configure + standalone toolchain, so this has gone undetected all along.
