Fix UAF in ngx_http_uploadprogress_event_handler

This UAF can be reached when compiling with --with-debug.

Fixes #61

ngx_http_uploadprogress_module.c

 
 
     if (shm_zone == NULL) {
-        ngx_http_uploadprogress_strdupfree(id);
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
                        "upload-progress: read_event_handler no shm_zone for id: %V", id);
+        ngx_http_uploadprogress_strdupfree(id);
         return;
     }