aprsc 2.1.21: Debian 13, Fedora 42/43, and thread titles

[Heikki Hannikainen]

aprsc 2.1.21 is now available.

Upgrading on Debian / Ubuntu:

sudo apt update && sudo apt upgrade
sudo reboot (to run the new kernel if it was updated)

Upgrading on Fedora:

sudo dnf upgrade
sudo reboot (to run the new kernel if it was updated)

FreeBSD:

http://he.fi/aprsc/down/

Changes:

* hlog,autoconf: Fix building on MacOS (for development environment)

* config: Add DisallowIgateCall to drop packets by igate call or Q
construct (allows filtering the text messaging loops caused by the Aurora
software)

* login: Reject client when "filter" appears as version number or version
is missing (client bug, the application version is missing or not
separated by a space).

If a filter was sent, it would have been ignored as "filter" was
interpreted as the version number, and the client would not get the
packets it wanted.

The change is worth noting, since it will block at least the old versions
iot4pi_LoRaGW-0.1 which caused messaging loops already in February 2026.
ftp://www.lora-aprs.at has version 0.7 which should fix the loops and also
send a version number with a space between the software name ad version.

- Hessu