WIP: Extend frame tracing to decode the performative payloads

This should probably only try to decode the transfer performative. But
currently the frame dumper has no way to feed back anything about the
AMQP value it just dumped.

c/src/core/logger.c

@@ -226,6 +226,11 @@ void pni_logger_log_msg_frame(pn_logger_t *logger, pn_log_subsystem_t subsystem,
   va_end(ap);
   size_t psize = pni_value_dump(frame, &output);
   pn_bytes_t payload = {.size=frame.size-psize, .start=frame.start+psize};
+  while (payload.size>0 && psize>0) {
+    pn_fixed_string_append(&output, pn_string_const(" ", 1));
+    psize = pni_value_dump(payload, &output);
+    payload = (pn_bytes_t){.size=payload.size-psize, .start=payload.start+psize};
+  }
   if (payload.size>0) {
     pn_fixed_string_addf(&output, " (%zu) ", payload.size);
     pn_fixed_string_quote(&output, payload.start, payload.size);