Bugfix: read event was not blocked after reading body.

Read event should be blocked after reading body, else undefined behaviour
might occur on additional client activity.  This fixes segmentation faults
observed with proxy_ignore_client_abort set.

src/http/ngx_http_request_body.c

@@ -378,6 +378,8 @@ ngx_http_do_read_client_request_body(ngx_http_request_t *r)
         rb->bufs = rb->bufs->next;
     }
 
+    r->read_event_handler = ngx_http_block_reading;
+
     rb->post_handler(r);
 
     return NGX_OK;