package/util-linux: disable systemd for host build

package/util-linux: disable systemd for host build

When building host-util-linux, the systemdsystemunitdir is set to the
real host directory, so the install step fails with:

/usr/bin/install: cannot remove '/usr/lib/systemd/system/fstrim.service': Permission denied
/usr/bin/install: cannot remove '/usr/lib/systemd/system/fstrim.timer': Permission denied

Since we don't need systemd support in host-util-linux, unconditionally
disable it for the host build.

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>