Allow ntlm_auth to have a --winbindd_priviliedged socket location option

[Arnab Roy]

Hi ,

I know I am doing this at my own peril but , I need to specify a custom
location for ntlm_auth for the winbind priv pipe ,

I found the relevant section in the code that seems to be doing this under
nsswitch/wb_common.c

static const char *winbindd_socket_dir(void)
{
        if (nss_wrapper_enabled()) {
                const char *env_dir;

                env_dir = getenv("SELFTEST_WINBINDD_SOCKET_DIR");
                if (env_dir != NULL) {
                        return env_dir;
                }
        }

        return WINBINDD_SOCKET_DIR;
}

But that seems to be looking for an environment variable rather than CLI
option..my C is not great :( any help is appreciated.

TIA
Arnab