libHX from server:mail project

For 16.0 run the following as root:

zypper addrepo https://download.opensuse.org/repositories/server:mail/16.0/server:mail.repo
zypper refresh
zypper install libHX

For 15.7 run the following as root:

zypper addrepo https://download.opensuse.org/repositories/server:mail/15.7/server:mail.repo
zypper refresh
zypper install libHX

For 15.6 run the following as root:

zypper addrepo https://download.opensuse.org/repositories/server:mail/15.6/server:mail.repo
zypper refresh
zypper install libHX