[truetype] Integer overflows. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2270 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2278 * src/truetype/ttinterp.c (Ins_MDRP, _iup_worker_interpolate): Use ADD_LONG and SUB_LONG.