Ensure that sprite aligner click to pick sprites is thread safe

Use a mutex for list of sprite IDs found in (threaded) draw jobs

src/gfx.cpp

@@ -1212,7 +1212,7 @@ static void GfxBlitter(const GfxBlitterCtx &ctx, const Sprite *sprite, int x, in
 		if (topleft <= clicked && clicked <= bottomright) {
 			uint offset = (((size_t)clicked - (size_t)topleft) / (blitter->GetScreenDepth() / 8)) % bp.pitch;
 			if (offset < (uint)bp.width) {
-				include(_newgrf_debug_sprite_picker.sprites, sprite_id);
+				_newgrf_debug_sprite_picker.FoundSpriteDuringDrawing(sprite_id);
 			}
 		}
 	}