[cff, truetype] Integer overflows. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2075 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2088 * src/cff/cf2font.c (cf2_font_setup): Use OVERFLOW_MUL_INT32. * src/truetype/ttinterp.c (Ins_ISECT): Use OVERFLOW_MUL_LONG, OVERFLOW_ADD_LONG, and OVERFLOW_SUB_LONG.