package/ejabberd: bump to version 19.09.1

There are two remainning patches to:

- change the Makefile rules so dependencies are not downloaded/compiled;
- fix ejabberd user in ejabberdctl script.

The erlang-p1-iconv package is not anymore a dependency for ejabberd.

Signed-off-by: Johan Oudinet <johan.oudinet@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>