Cleanup : rename Set_mode_SDL() to GFX2_Set_mode()

src/graph.c

@@ -400,11 +400,7 @@ try_again:
 
   if (screen_changed)
   {
-#if defined(USE_SDL) || defined(USE_SDL2)
-    Set_mode_SDL(&width, &height,fullscreen);
-#else
     GFX2_Set_mode(&width, &height, fullscreen);
-#endif
   }
 
   if (screen_changed || pixels_changed)

src/sdlscreen.c

@@ -114,7 +114,7 @@ void Screen_FillRect(int x, int y, int w, int h, byte color)
 }
 
 /// Sets the new screen/window dimensions.
-void Set_mode_SDL(int *width, int *height, int fullscreen)
+void GFX2_Set_mode(int *width, int *height, int fullscreen)
 {
   static SDL_Cursor* cur = NULL;
   static byte cursorData = 0;

src/sdlscreen.h

@@ -33,8 +33,6 @@
 #include "struct.h"
 #include "global.h"
 
-void Set_mode_SDL(int *,int *,int);
-
 GFX2_GLOBAL SDL_Rect ** List_SDL_video_modes;
 
 ///