Add macOS block to fix warning for differences in getgrouplist().

getgrouplist() is not POSIX, so it varies between platforms.

src/common/group_cache.c

@@ -166,8 +166,17 @@ static int _group_cache_lookup_internal(gids_cache_needle_t *needle, gid_t **gid
 
 	/* Cache lookup failed or entry value was too old, fetch new
 	 * value and insert it into cache.  */
+#if defined(__APPLE__)
+	/*
+	 * macOS has (int *) for the third argument instead
+	 * of (gid_t *) like FreeBSD, NetBSD, and Linux.
+	 */
+	while (getgrouplist(entry->username, entry->gid,
+			    (int *)entry->gids, &entry->ngids) == -1) {
+#else
 	while (getgrouplist(entry->username, entry->gid,
 			    entry->gids, &entry->ngids) == -1) {
+#endif
 		/* group list larger than array, resize array to fit */
 		entry->gids = xrealloc(entry->gids,
 				       entry->ngids * sizeof(gid_t));

src/plugins/mcs/group/mcs_group.c

@@ -127,7 +127,15 @@ static int _get_user_groups(uint32_t user_id, uint32_t group_id,
 
 	user_name = uid_to_string((uid_t) user_id);
 	*ngroups = max_groups;
+#if defined(__APPLE__)
+	/*
+	 * macOS has (int *) for the third argument instead
+	 * of (gid_t *) like FreeBSD, NetBSD, and Linux.
+	 */
+	rc = getgrouplist(user_name, (gid_t) group_id, (int *) groups, ngroups);
+#else
 	rc = getgrouplist(user_name, (gid_t) group_id, groups, ngroups);
+#endif
 
 	if (rc < 0) {
 		error("getgrouplist(%s): %m", user_name);