sound blaster lib: add config options for DSP 4.xx FIFO enable, for
autoinit and single-cycle playback modes, for testing. Made autoinit
default to using FIFO, and single-cycle default to NOT using FIFO. Also
just noticed, is that Creative Documentation doesn't explicitly list the
meaning of the bitfields but it does recommend 0xB0/0xC0 for
single-cycle or 0xB6/0xC6 for autoinit, matching the new defaults listed
above. Added menu options to control these settings. Added code to
remove a whole bunch of menu items for 16-bit small/compact memory
models because we went past the 64KB limit imposed by Watcom linker.