[cff, truetype] Integer overflows. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2047 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2057 * src/cff/cf2hints.c (cf2_hintmap_map): Use OVERFLOW_SUB_INT32. * src/truetype/ttinterp.c (Ins_ADD): Use OVERFLOW_ADD_LONG. (Ins_SUB): Use OVERFLOW_SUB_LONG. (Ins_NEG): Use NEG_LONG.