core: print runtime dir in log message

- do logging to syslog, along with stderror for runtime dir related
  errors

main.c

@@ -2358,12 +2358,14 @@ try_again:
 	/* create runtime dir if doesn't exist */
 	if (stat(runtime_dir, &st) == -1) {
 		if(mkdir(runtime_dir, 0700) == -1) {
-			fprintf(stderr,  "failed to create runtime dir\n");
+			LM_ERR("failed to create runtime dir %s\n", runtime_dir);
+			fprintf(stderr,  "failed to create runtime dir %s\n", runtime_dir);
 			goto error;
 		}
 		if(sock_uid!=-1 || sock_gid!=-1) {
 			if(chown(runtime_dir, sock_uid, sock_gid) == -1) {
-				fprintf(stderr,  "failed to change owner of runtime dir\n");
+				LM_ERR("failed to change owner of runtime dir %s\n", runtime_dir);
+				fprintf(stderr,  "failed to change owner of runtime dir %s\n", runtime_dir);
 				goto error;
 			}
 		}