libobs/graphics: Always load gif frame if needed

Under certain circumstances it's necessary to seek, but if the frame
isn't loaded for the position that's being seeked to, it won't update
the texture.  This just ensures the texture will update when seeking.

libobs/graphics/image-file.c

@@ -318,9 +318,10 @@ void gs_image_file_update_texture(gs_image_file_t *image)
 	if (!image->is_animated_gif || !image->loaded)
 		return;
 
-	if (image->animation_frame_cache[image->cur_frame]) {
-		gs_texture_set_image(image->texture,
-				image->animation_frame_cache[image->cur_frame],
-				image->gif.width * 4, false);
-	}
+	if (!image->animation_frame_cache[image->cur_frame])
+		decode_new_frame(image, image->cur_frame);
+
+	gs_texture_set_image(image->texture,
+			image->animation_frame_cache[image->cur_frame],
+			image->gif.width * 4, false);
 }