package/netopeer2: add dependency to host-sysrepo

package/netopeer2: add dependency to host-sysrepo

The sysrepoctl executable from the host-sysrepo package is used to
install YANG modules during installation. So add the dependency here.
Also make sure we use this executable by setting the make environment
variable SYSREPOCTL_EXECUTABLE. Otherwise a system wide installed
sysrepoctl would be used that is not what we want.

Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>