seccomp: add rseq() to default list of syscalls to whitelist

Apparently glibc is going to call this implicitly soon, hence let's
whitelist this by default.

Fixes: #12127

src/shared/seccomp-util.c

@@ -291,6 +291,7 @@ const SyscallFilterSet syscall_filter_sets[_SYSCALL_FILTER_SET_MAX] = {
                 "pause\0"
                 "prlimit64\0"
                 "restart_syscall\0"
+                "rseq\0"
                 "rt_sigreturn\0"
                 "sched_yield\0"
                 "set_robust_list\0"