Missing header.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Notable changes:
* Move some plugins from libelektra-plugins to libelektra-cpp because
  they got reimplemented in C++.
* New package libelektra-zmq
* Move the crypto plugin from libopenssl to libgcrypt
* Disable host build: elektra doesn't need it anymore and nobody uses
  kdb during package builds for now.

Closes: #12307

Signed-off-by: Harald Geyer <harald@ccbib.org>

Signed-off-by: Rosen Penev <rosenp@gmail.com>