Introduc Eina_Log. Now to print informations or erros, please use eina_log and the define WRN, ERR, CRIT, DBG and INF.
Tiis turorial explain how to use eina_log http://docs.enlightenment.org/auto/edje/tutorial_log_page.html
Basically you just need to export of define EINA_LOG_LEVELS=emqtt:5 on your system to get full debug informations.

to get only informations (INF) : EINA_LOG_LEVELS=emqtt:3 emqtt_sn_broker