cff.cpp: Check minimum size of packed stream before calling unpacker
cff.cpp: Check minimum size of packed stream before calling unpacker

Don't even try to unpack the module if the recorded size is
less than the unpacker's header id. This should fix the issues
with fuzzing samples i-110_048.cff and i-110_105.cff that don't
reproduce in my setup (due to different ASAN version, probably).

Bug: https://github.com/adplug/adplug/issues/110

adplug/adplug,adplug/adplug