Changed hardcoded 30 to object counter

Replaced hard coded limit of 30 AudioPlayers with s_freeObjectsAvailable
that starts at 32.
OpenSL ES for Android supports a single engine per application, and up
to 32 objects. Available device memory and CPU may further restrict the
usable number of objects.

http://mobilepearls.com/labs/native-android-api/ndk/docs/opensles/index.html

Replaced some indentations using spaces with tabs (like the rest of the
file).