(SDL2) List available renderers
(SDL) Clean sdl_gfx.c up a bit
(SDL) Fix scaler memory leak
(SDL*) Refactor *set_handles() functions
Show image frame before BFI black frame

Image frame should be shown as soon as possible to minimize display
latency.
Merge pull request #907 from mprobinson/master

Show image frame before BFI black frame
Merge pull request #906 from heuripedes/sdl-improvements

SDL/SDL2 gfx clean ups
Merge pull request #905 from heuripedes/haiku

Haiku fixes
Implement frame delay option

Sets how many milliseconds to delay after VSync before running the core.
Fix newlines and spaces
Make frame delay description clearer
Merge pull request #908 from mprobinson/master

Implement frame delay option
Fix dangling pointer. Likely cause for crashes; could be that mingw64 crash.
Apply the same fix to another part of the code.
Fix check_volume
(Menu) Don't do scrolling acceleration for menu
(qb) Always call the correct pkg-config
Merge pull request #911 from heuripedes/master

(qb) Always call the correct pkg-config
Allow unix-like build under mingw
Merge pull request #912 from heuripedes/mingw-configure

Allow unix-like build under mingw