Add debug warning when maximum session limit is hit for a specified user group

raptorsmiface/libraptorsmiface.c

@@ -705,6 +705,7 @@ bool raptor_sm_sesslimit_reached(char* username) {
 			mysql_close(conn);
 			return false;
 		}
+		dprint("[WARNING] Maximum session limit reached for group '%s'!\n", groupname);
 		free(groupname);
 		mysql_close(conn);
 		return true;