video: Let video targets optionally decide their default OpenGL configs.

This is necessary because the Raspberry Pi is a strange beast, that believes
it has OpenGL support (through glX?) but generally has GLES2 support.

So when using the raspberry video target, we need to force this to default
to a GLES2 context, or by default SDL_CreateWindow() will fail, deep down
when it tries to load the proper GL library.

Fixes testsprite2 (and basically everything else that wasn't testgles2) when
run on a Raspberry Pi without a X server.

Please note that other targets might also need this filled in, the Raspberry
Pi is just the most prominent and readily-available System-On-A-Chip style
thing on my desk.  :)

src/video/raspberry/SDL_rpiopengles.c

@@ -27,6 +27,14 @@
 
 /* EGL implementation of SDL OpenGL support */
 
+void
+RPI_GLES_DefaultProfileConfig(_THIS, int *mask, int *major, int *minor)
+{
+    *mask = SDL_GL_CONTEXT_PROFILE_ES;
+    *major = 2;
+    *minor = 0;
+}
+
 int
 RPI_GLES_LoadLibrary(_THIS, const char *path) {
     return SDL_EGL_LoadLibrary(_this, path, EGL_DEFAULT_DISPLAY, 0);

src/video/raspberry/SDL_rpiopengles.h

@@ -40,6 +40,7 @@ extern int RPI_GLES_LoadLibrary(_THIS, const char *path);
 extern SDL_GLContext RPI_GLES_CreateContext(_THIS, SDL_Window * window);
 extern int RPI_GLES_SwapWindow(_THIS, SDL_Window * window);
 extern int RPI_GLES_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context);
+extern void RPI_GLES_DefaultProfileConfig(_THIS, int *mask, int *major, int *minor);
 
 #endif /* SDL_VIDEO_DRIVER_RPI && SDL_VIDEO_OPENGL_EGL */
 

src/video/raspberry/SDL_rpivideo.c

@@ -123,6 +123,7 @@ RPI_Create()
     device->GL_GetSwapInterval = RPI_GLES_GetSwapInterval;
     device->GL_SwapWindow = RPI_GLES_SwapWindow;
     device->GL_DeleteContext = RPI_GLES_DeleteContext;
+    device->GL_DefaultProfileConfig = RPI_GLES_DefaultProfileConfig;
 
     device->PumpEvents = RPI_PumpEvents;