[Ohrrpgce] SVN: teeemcee/13422 blackbox: don't sleep, instead rely on gfx_present and gfx_wait_one_fram

[subversion at HamsterRepublic.com]

teeemcee
2023-12-21 13:23:04 -0800 (Thu, 21 Dec 2023)
178
blackbox: don't sleep, instead rely on gfx_present and gfx_wait_one_frame to pass the time

Add #define BACKEND_GOVERNED_FRAMERATE.
This could be made a runtime option in future.
---
U   wip/allmodex.bas
U   wip/gfx_sdl2.bas
U   wip/os.bi
U   wip/os.h