I've made it so that `Graphics.update` pauses the Ruby VM and returns to
the libretro frontend. Once the libretro frontend calls `retro_run()`
again, the Ruby VM resumes. This allows the libretro frontend to control
the rendering loop.
I've decided to stop gambling with ways to make `-e` not crash Ruby on
startup in libretro builds (see commit
1473416a5a for context). Making Ruby load
a dummy script seems to work better.
Guys, I think I'm going insane. Every time I build the libretro Ruby
sandbox with a different version of Ruby, or even when I build Ruby at a
different path on my computer, there's some chance that the builds
produced with that version of Ruby and/or that path on my computer
result in Ruby crashing on startup in libretro builds. I've been
tweaking these command-line arguments that are passed to Ruby for a
while now, and I *think* these are the correct ones that will stop Ruby
from crashing.
