Name already in use

Per Debian Policy Manual section 12.5, and lintian warning
extra-license-file, the entirety of the CDDL is contained in the
debian/copyright file which is included with each package. As such,
including the OPENSOLARIS.LICENSE file in each package as well is
redundant and unneccessary.

Only include specific utilities needed for use in a udeb environment.
This effectively excludes unneeded utilities like zdb, zhack, zinject
and the like.

Use DEB_BUILD_GNU_TYPE DEB_HOST_GNU_TYPE from dpkg-architecture to
set the build and host architectures. This allows building an i386
package set in an i386 chroot running an amd64 kernel. Without this,
the running kernel version is used for detection and tries to build
the x86_64 assembly in spl, which fails with unknown registers since
the actual compiler is i386.

This reverts commit c02653e.

Upstream version 0.6.2

prerm will not be called with `purge` parameter.

This reverts commit 9ab1c6d.

If /etc/zfs/ isn't present or isn't a directory, zpool.cache
won't be created when importing a pool. Also we need to make
sure when users purges the package zpool.cache is removed as
well.

zpool.cache does not need to be kept on user's system when
the package is purged since information in it is only some
status about the host and mounts. The only direct harm of
not having it is that users need to import the pool by hand
and specify -f parameter.