Factored out more version-specific SDL code to clean up several renderer functions.
Factored out more version-specific SDL code to clean up several renderer functions.

grimfang4/sdl-gpu,masonwheeler/sdl-gpu,ademuri/sdl-gpu,Helios-vmg/sdl-gpu,grimfang4/sdl-gpu,Helios-vmg/sdl-gpu,grimfang4/sdl-gpu,ademuri/sdl-gpu,masonwheeler/sdl-gpu,grimfang4/sdl-gpu,masonwheeler/sdl-gpu,ademuri/sdl-gpu,Helios-vmg/sdl-gpu,Helios-vmg/sdl-gpu,ademuri/sdl-gpu,masonwheeler/sdl-gpu