[cff] Integer overflow. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2109 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2110 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2122 * src/cff/cf2blues.c (cf2_blues_init): Use OVERFLOW_SUB_INT32. * src/cff/cf2hints.c (cf2_hintmap_map): Synchronize if-else branches.