[cff] Integer overflows. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2200 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2210 * src/cff/cf2hints.c (cf2_hintmap_insertHint): Use SUB_INT32 and ADD_INT32. * src/cff/cf2intrp.c (cf2_interpT2CharString) <cf2_cmdVMOVETO>: Use ADD_INT32.