score.c: Use the new OSL_DONT_FREE flag for the aft column.

score.c: Use the new OSL_DONT_FREE flag for the aft column.

The score tables stores in one of its columns a pointer to
a row in the audio file table. This means for each admissible
file we're allocating space for a void* pointer to store the
aft pointer.

It's simpler and probably faster to store the afs pointer directly,
but of course that pointer must not be freed by the osl.