Remove scene_flip function

It was a bug to call this function outside of sact_Update, because it
set scene_is_dirty to false without first rendering the scene. This can
cause the scene to not be rendered in a timely manner.

include/scene.h

@@ -44,7 +44,6 @@ extern bool scene_is_dirty;
 void scene_register_sprite(struct sprite *sp);
 void scene_unregister_sprite(struct sprite *sp);
 void scene_render(void);
-void scene_flip(void);
 int scene_set_wp(int cg_no);
 int scene_set_wp_color(int r, int g, int b);
 void scene_set_sprite_z(struct sprite *sp, int z);

src/hll/SACT2.c

@@ -138,7 +138,8 @@ int sact_Update(void)
 	dungeon_update();
 	if (scene_is_dirty) {
 		scene_render();
-		scene_flip();
+		gfx_swap();
+		scene_is_dirty = false;
 	}
 	return 1;
 }

src/input.c

@@ -298,7 +298,7 @@ void handle_events(void)
 		case SDL_WINDOWEVENT:
 			switch (e.window.event) {
 			case SDL_WINDOWEVENT_EXPOSED:
-				scene_flip();
+				gfx_swap();
 				break;
 			case SDL_WINDOWEVENT_ENTER:
 				mouse_focus = true;
@@ -314,7 +314,7 @@ void handle_events(void)
 				break;
 			case SDL_WINDOWEVENT_SIZE_CHANGED:
 				gfx_update_screen_scale();
-				scene_flip();
+				gfx_swap();
 				break;
 			}
 			break;

src/scene.c

@@ -81,12 +81,6 @@ void scene_render(void)
 	}
 }
 
-void scene_flip(void)
-{
-	gfx_swap();
-	scene_is_dirty = false;
-}
-
 int scene_set_wp(int cg_no) {
 	if (!cg_no) {
 		gfx_delete_texture(&wp);