Fixed bug 1583 - Fix build for disabled SDL render subsystem

Marcus von Appen

If one wants to disable the SDL render subsystem, the build breaks on several platforms due to an empty render_drivers array in SDL_render.c.
Fixed bug 1582 - Allow disabling SDL_VIDEO_DRIVER_WINDOWS

Marcus von Appen

Trying to build SDL 2.x (HG) on Win32 platforms with either VS.NET or MinGW requires one to have the video subsystem and SDL_VIDEO_DRIVER_WINDOWS flag enabled due to the helper window creation routines.

The attached patch changes the helper window creation behaviour, so that one can build SDL2 without the video subsystem or Windows video drivers on Win32 platforms.