src: Print flags in DATA

src/app_helper.cc

@@ -377,6 +377,11 @@ void print_data_frame(print_type ptype, uint16_t length, uint8_t flags,
   printf("%sDATA%s frame (length=%d, flags=%d, stream_id=%d)\n",
          frame_name_ansi_esc(ptype), ansi_escend(),
          length, flags, stream_id);
+  if(flags) {
+    nghttp2_frame_hd hd = {length, NGHTTP2_DATA, flags, stream_id};
+    print_frame_attr_indent();
+    print_flags(hd);
+  }
 }
 } // namespace