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.
Previously if "$rootok" = 1, parsing of netroot command line arguments
was skipped. For multiple netroot arguments, all parse scripts have to
run.
Previously only the first netroot argument was taken into account for
the parsing scripts. Now every netroot argument is processed.