message: util: Define SECCOMP_RET_KILL_PROCESS if not provided by the headers
  Define `SECCOMP_RET_KILL_PROCESS` as it isn't defined in the headers, as
  is the case for the GUIX build on this platform.
diff: @@ -40,6 +40,10 @@ bool g_syscall_sandbox_log_violation_before_terminating{false};
  #error Syscall sandbox is an experimental feature currently available only under Linux x86-64.
  #endif // defined(__x86_64__)
  +#ifndef SECCOMP_RET_KILL_PROCESS
  +#define SECCOMP_RET_KILL_PROCESS 0x80000000U
  +#endif
  +
  // This list of syscalls in LINUX_SYSCALLS is only used to map syscall numbers to syscall names in
  // order to be able to print user friendly error messages which include the syscall name in addition
  // to the syscall number.
  