SDL: Use whatever display SDL gives us for EGL.

SDL/SDLGLGraphicsContext.h

@@ -7,11 +7,6 @@
 #include "gfx/gl_common.h"
 #include "Common/GraphicsContext.h"
 
-// TODO: Move this to a better place.
-#if defined(USING_EGL)
-int8_t EGL_Open();
-#endif
-
 class SDLGLGraphicsContext : public DummyGraphicsContext {
 public:
 	SDLGLGraphicsContext() {
@@ -54,5 +49,3 @@ private:
 	SDL_GLContext glContext = nullptr;
 	GLRenderManager *renderManager_ = nullptr;
 };
-
-