nghttpx: Fix stall when TLS follows after proxy protocol

This fixes that nghttpx stalls when TLS handshake and data follow
after proxy protocol header and no extra read notification is
triggered (e.g., just small 1 HTTP request).

src/shrpx_rate_limit.cc

@@ -108,7 +108,8 @@ void RateLimit::stopw() {
 }
 
 void RateLimit::handle_tls_pending_read() {
-  if (!conn_ || !conn_->tls.ssl || !conn_->tls.initial_handshake_done ||
+  if (!conn_ || !conn_->tls.ssl ||
+      (conn_->tls.rbuf.rleft() == 0 && !conn_->tls.initial_handshake_done) ||
       (SSL_pending(conn_->tls.ssl) == 0 && conn_->tls.rbuf.rleft() == 0 &&
        conn_->tls.earlybuf.rleft() == 0)) {
     return;