Fix how the templates are merged

It was impossible to inherit the templates from an higher config level,
because the templates were overwritten when the config were merged.

Signed-off-by: Brice Figureau <brice@daysofwonder.com>

ngx_http_uploadprogress_module.c

     ngx_uint_t                            i;
 
     if (conf->shm_zone == NULL) {
-        *conf = *prev;
+        conf->shm_zone = prev->shm_zone;
+        conf->timeout = prev->timeout;
+        conf->cleanup = prev->cleanup;
+        conf->handler = prev->handler;
+        conf->track = prev->track;
     }
 
     ngx_conf_merge_str_value(conf->content_type, prev->content_type, "text/javascript");