Right now, a few places in the frontend code still use printf and
consorts. We mark the affected files with a FIXME for now, and
add a dedicated exception for each. To be fixed!
Also tweak FORBIDDEN_SYMBOL_REPLACEMENT to hopefully really always
enforce a compiler error
Based on the SONiVOX® Embedded Audio Synthesis (EAS™) library, which is
part of the base Android OS.
CPU stats (Cortex A8 1GHz, monkey1 intro, peak values):
MAME OPL: 30%
DosBox OPL: 26%
EAS: 19%
This in turn enables modifying MidiDriver_MPU401::close() to allow
it to be called on a midi driver that has not yet been opened.
The specific issue that triggered me to make these changes was a
crash-upon-quit in HUGO, caused by it instantiating a midi driver,
then encountering an error (missing hugo.dat) *before* having
opened the new midi driver; the general cleanup code then tries
to close the (not yet opened) midi driver -> kaboom
Also fixed some engines which were leaking MidiDriver instances.