[truetype] Mask numeric overflows. * src/truetype/ttinterp.c (Move_CVT, Move_CVT_Stretched, Ins_MIRP): Mask numeric overflows. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11681 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11734