Update c->sent in ngx_ssl_send_chain() even if SSL buffer is not used.

src/event/ngx_event_openssl.c

diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index 21deefd..7903eb6 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -995,6 +995,7 @@
             }
 
             in->buf->pos += n;
+            c->sent += n;
 
             if (in->buf->pos == in->buf->last) {
                 in = in->next;