Improve compliance with GNUCS chapter 7.2.2.

In the debian/rules file, substitute

  * $(CHMOD) for chmod.
  * $(INSTALL) for mkdir.
  * $(MAKE) for make.

pursuant to the GNU Coding Standard, chapter 7.2.2, regarding Makefiles.

Only $(MAKE) is likely to be defined in the Launchpad build environment outside
of an autotools job, so protect all three variables with a default assignment.
Ensure that DKMS automake stubs are not executable.

Resolve this lintian warning:

	W: zfs-dkms: executable-not-elf-or-script usr/src/zfs-0.6.3/dracut/90zfs/parse-zfs.sh.in
	W: zfs-dkms: executable-not-elf-or-script usr/src/zfs-0.6.3/dracut/90zfs/mount-zfs.sh.in
	W: zfs-dkms: executable-not-elf-or-script usr/src/zfs-0.6.3/dracut/90zfs/module-setup.sh.in

Also change the null command to a comment in the printf command.
Move libzfs-dev symlinks from /lib to /usr/lib.

Resolve this lintian error:

	W: libzfs2: dev-pkg-without-shlib-symlink lib/libzfs.so.2.0.0 usr/lib/libzfs.so
	W: libzfs2: dev-pkg-without-shlib-symlink lib/libzfs_core.so.1.0.0 usr/lib/libzfs_core.so

Quoting https://lintian.debian.org/tags/dev-pkg-without-shlib-symlink.html

  The symlink is generally expected in the same directory as the library
  itself. The major exception to this rule is if the library is installed
  in (or beneath) /lib, where the symlink must be installed in the same
  dir beneath /usr.