Typing Control-C in Terminal app causes an interrupt signal that should enter the DPPC debugger but this only worked once since the signal handler never returned. Even if the signal handler reenabled the signal somehow, it calls enter_debugger recursively which is strange since the earlier calls to enter_debugger would never return.
Now the signal handler just sets a flag (power_on) which can be used to exit any loop (emulator loops, stepping loops, disassembly loops, dumping loops).
Main always calls enter_debugger now which calls the ppc_exec loop. The power_on flag will exit the ppc_exec loop to return to the debugger. Recursion of enter_debugger is eliminated except for calls to loguru's ABORT_F.
An enum power_off_reason is used to indicate why the power_on flag is set to false and to determine what happens next.
Result of running IWYU (https://include-what-you-use.org/) and
applying most of the suggestions about unncessary includes and
forward declarations.
Was motivated by observing that <thread> was being included in
ppcopcodes.cpp even though it was unused (found while researching
the use of threads), but seems generally good to help with build
times and correctness.
While Emscripten has an SDL compabtility layer, it assumes that the
code is executing in the main browser process (and thus has access to
them DOM). The Infinite Mac project runs emulators in a worker thread
(for better performance) and has a custom API for the display, sound,
input, etc. Similarly, it does not need the cross-platform sound support
from cubeb, there there is a sound API as well.
This commit makes SDL (*_sdl.cpp) and cubeb-based (*_cubeb.cpp) code be
skipped when targeting Emscripten, and instead *_js.cpp files are used
instead (this is the cross-platform convention used by Chromium[^1], and
could be extended for other targets).
For hostevents.cpp and soundserver.cpp the entire file was replaced,
whereas for videoctrl.cpp there was enough shared logic that it was
kept, and the platform-specific bits were moved behind a Display class
that can have per-platform implementations. For cases where we need
additional private fields in the platform-specific classes, we use
a PIMPL pattern.
The *_js.cpp files with implementations are not included in this
commit, since they are closely tied to the Infinite Mac project, and
will live in its fork of DingusPPC.
[^1]: https://www.chromium.org/developers/design-documents/conventions-and-patterns-for-multi-platform-development/
