rootfs is on nbd
In not hostonly mode, require_binaries will still complain.
If in hostonly mode and the module is explicitly added via -a nbd, then
install() section will still complain later:
dracut-install: ERROR: installing 'nbd-client'
Signed-off-by: Thomas Renninger <trenn@suse.de>
Add new functions require_binaries() and require_any_binary() to be used
in the check() section of module-setup.sh.
These functions print a warning line telling the user, which binary is
missing for the specific dracut module.
This unifies the way of checking for binaries and makes the life of an
initramfs creator easier, if he wants to find out why a specific dracut
module is not included in the initramfs.
Thomas Renninger