This allows a big swath of ifdefs to be removed. It also means savings as the db var is not passed around all of the time, and makes it easier to remove the final broker call to mosquitto_time() call in packet_mosq.c. In one test this reduced the calls to mosquitto_time() from 295k to 48k.
* Fix Will message for a persistent client incorrectly being sent when the client reconnects after a clean disconnect.
* Fix Will message for a persistent client not being sent on disconnect.
* Fix mosquitto_pub not using the `-c` option.
Thanks to Yannic Schröder.
Closes#1273.