mkj/dropbear DROPBEAR_2020.80

Dropbear 2020.80

on GitHub

Don't block authorized_keys logins with no-X11-forwarding or no-agent-forwarding
restrictions when X11 or agent forwarding are disabled at compile time.
This is more of a problem now X11 is disabled by default, reported by Guilhem Moulin

Reduce binary size by 4kB (x64) when using bundled libtommath

Define GNU_SOURCE for getrandom() on uclibc, reported by Laurent Bercot and
Fabrice Fontaine

Improve checking libtomcrypt version compatibility

Add some style notes to DEVELOPING.md