Fix white flash levelshot bug in OpenGL1

If you tried to draw the last loaded image, gl texture 0 (which is appearently white)
was used because renderer thought the image was already bound.

Why OpenGL1 renderer binds texture 0, I have no idea. It's been removed from OpenGL2.

code/renderergl2/tr_model.c

@@ -1147,11 +1147,6 @@ void RE_BeginRegistration( glconfig_t *glconfigOut ) {
 	RE_ClearScene();
 
 	tr.registered = qtrue;
-
-	// NOTE: this sucks, for some reason the first stretch pic is never drawn
-	// without this we'd see a white flash on a level load because the very
-	// first time the level shot would not be drawn
-//	RE_StretchPic(0, 0, 0, 0, 0, 0, 1, 1, 0);
 }
 
 //=============================================================================