This removes libco and all the usages of it (+pthreads).
Rewired all dynarecs and interpreter to return after every frame so that
libretro can process events. This required to make dynarec re-entrant.
Dynarecs were updated to check for new frame on every update (IRQ, cycle
exhaustion, I/O write, etc). The performance impact of doing so should
be minimal (and definitely outweight the libco gains). While at it,
fixed small issues to get a bit more perf: arm dynarec was not idling
correctly, mips was using stack when not needed, etc.
Tested on PSP (mips), OGA (armv7), Linux (x86 and interpreter). Not
tested on Android though.
I think this does not make a difference at all in the code, since PC is
treated in a special way anyway (reloaded with an immediate when read
and treated as an indirect branch when written). However for the sake of
completeness I'm undoing what I did. (The comma fix stays :P)
Turns out there were a couple of very interesting and hard to track
bugs. A missing comma made the reg list too short, leaving the 31th
element at the mercy of the linker ordering algorithm, which seems to
work in some cases depending on the compiler version.
Also the cache flush code seemed not to work on my machine (OGA),
not sure why it wored in the past :/
Not available on iOS/Android, only probably there on OpenPandora.
On top of that iOS 8+ deprecated the system() call, so would
probably be becoming obsolete on that platform.