is_negated_errno: support large errno values

Thanks to SECCOMP_RET_DATA == 0xffff, abnormally large errno
values could be easily seen when a seccomp filter is used, e.g.
BPF_STMT(BPF_RET, SECCOMP_RET_ERRNO | SECCOMP_RET_DATA)

* syscall.c (is_negated_errno): Allow errno values as large as 0xffff.
1 file changed