If the current process has unlimited RLIMIT_MEMLOCK,
we should should leave it as is.

Fixes: 941ff6f1 ("bpf: fix rlimit in reuseport net selftest")
Signed-off-by: NJohn Sperbeck <jsperbeck@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>