SSL: avoid reading on pending SSL_write_early_data(). If SSL_write_early_data() returned SSL_ERROR_WANT_WRITE, stop further reading using a newly introduced c->ssl->write_blocked flag, as otherwise this would result in SSL error "ssl3_write_bytes:bad length". Eventually, normal reading will be restored by read event posted from successful SSL_write_early_data(). While here, place "SSL_write_early_data: want write" debug on the path.

--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -98,6 +98,7 @@ struct ngx_ssl_connection_s {
     unsigned                    try_early_data:1;
     unsigned                    in_early:1;
     unsigned                    early_preread:1;
+    unsigned                    write_blocked:1;
 };