Modify install-redhat target.

Make it install systemd units or SysV init scripts only. This simplifies packaging where also target directories are customized.
DKMS inter-module dependencies feature.

DKMS does not handle simple scenarios like spl->zfs->lustre required build order discovery when both zfs and lustre DKMS RPMs have correctly provided a dkms.conf config-file with respectively BUILD_DEPENDS[0]="spl" and BUILD_DEPENDS[0]="zfs" statements.

The problem is that upon 1st reboot/autoinstall, DKMS seems to correctly detect that all 3 modules need to be rebuilt, but then lustre-dkms is rebuilt without regards to its zfs dependency and fails, when in the same time spl-dkms is correctly rebuilt before zfs-dkms to satisfy their own inter-dependency. Upon 2nd reboot/autoinstall, lustre-dkms rebuild is again attempted and can succeed.

At least it fixes the spl->zfs->lustre scenario! It will also report module re-build failures due to missing dependencies.