[AD] Optimizing slice_fclose()

[Karl Robillard <krobillard@xxxxxxxx>]

I have a program that streams .OGG files which are embedded in a larger file 
package.   This requires the use of al_fopen_slice().  Now 
al_load_audio_stream_f() will take ownership of the slice handle, but I must 
still manage (i.e. close) the original file handle returned by al_fopen().

It may be more convenient for some use cases like this to have a file slice be 
'single use' and close it's parent handle when the slice is closed.  Just 
something to consider for the future.

So my code currently handles the 'master' file handle used by slices.  What 
concerns me more is the overhead incurred by the seek done by slice_fclose().
I switch music streams by calling al_destroy_audio_stream() followed by 
al_load_audio_stream_f() using a new slice.  For both the 'single use' and 
'switch stream' case this extra seek is unwanted.  It would be ideal if there 
were some flag that could be set via al_fopen_slice() to prevent this 
unnecessary seek.


-Karl