bsnmp: Use mkstemp when creating clients local socket

Reviewed by:	harti, rew
Sponsored by:   NetApp, Inc.
Sponsored by:   Klara, Inc.
X-NetApp-PR:    #72
Differential Revision:	https://reviews.freebsd.org/D34550

contrib/bsnmp/lib/snmpclient.c

@@ -1012,7 +1012,7 @@ open_client_local(const char *path)
 	snprintf(snmp_client.local_path, sizeof(snmp_client.local_path),
 	    "%s", SNMP_LOCAL_PATH);
 
-	if (mktemp(snmp_client.local_path) == NULL) {
+	if (mkstemp(snmp_client.local_path) == -1) {
 		seterr(&snmp_client, "%s", strerror(errno));
 		(void)close(snmp_client.fd);
 		snmp_client.fd = -1;