ws: fix compile error on centos 7 - very old compiler (#1359) * http: fix typo * ws: fix comile error On CentOS: CC ws.lo ws.c: In function 'get_ws_frame': ws.c:244:3: error: 'for' loop initial declarations are only allowed in C99 mode for (int i = 0; i < payload_len; i++) { ^ ws.c:244:3: note: use option -std=c99 or -std=gnu99 to compile your code