Fix 180-degree rotated buffers without Y_INVERT

When the compositor sends a buffer without the Y_INVERT flag, the
resulting image had it rotated by 180 degrees.

References: swaywm/sway#5818

render.c

@@ -104,10 +104,11 @@ cairo_surface_t *render(struct grim_state *state, struct grim_box *geometry,
 		cairo_matrix_translate(&matrix,
 			(double)output->geometry.width / 2,
 			(double)output->geometry.height / 2);
-		cairo_matrix_rotate(&matrix, get_output_rotation(output->transform));
 		cairo_matrix_scale(&matrix,
-			(double)raw_output_width / output_width * output_flipped_x,
+			(double)raw_output_width / output_width,
 			(double)raw_output_height / output_height * output_flipped_y);
+		cairo_matrix_rotate(&matrix, -get_output_rotation(output->transform));
+		cairo_matrix_scale(&matrix, output_flipped_x, 1);
 		cairo_matrix_translate(&matrix,
 			-(double)output_width / 2,
 			-(double)output_height / 2);