Log Message:
Upgrade to ExaBGP version 3.4.22.

Pkgsrc changes:
 * Adapt PLIST
 * Remove now-integrated patch

Upstream changes:

Version 3.4.22
  * Fix: issue with very fast route flapping
    patch by: Ravikumar Arunachalam

Version 3.4.21
  * Fix: make healthcheck work on netbsd
    patch by: he32
  * Fix: re-fix issue #493 Multiple IPv6 MPREACH attributes in one UPDATE
  * Fix: issue #732 --test not working for eBGP setup
  * Fix: possibly missing API message when sent at high rate, issue #736
    patch by: Ravikumar Arunachalam

Version 3.4.20
  * Fix: profiling
  * Fix: potential issue with networking (select on closed FD/TCP session)
  * Fix: issue with route replay order when sent fast
    patch by: Ravikumar Arunachalam