Fold in a minor fix from the removed linux-legacy branch to skip checking
character devices in /dev/ during import. Under Linux pread() may simply
block when reading from these devices causing the import to hang.
The majority of this this patch concerns itself with doing a direct
replacement of Solaris's libdiskmgt library with libblkid+libefi.
You'll notice that this patch removes all libdiskmgt code instead of
ifdef'ing it out. This was done to minimize any confusion when reading
the code because it seems unlikely we will ever port libdiskmgt to Linux.
Despite the replacement the behavior of the tools should have remained
the same with one exception. For the moment, we are unable to check
the partitions of devices which have an MBR style partition table when
creating a filesystem. If a non-efi partition sceme is detected on a
whole disk device we prompt the user to explicity use the force option.
It would not be a ton of work to make the tool aware of MBR style
partitions if this becomes a problem.
I've done basic sanity checking for various configurations and all
the issues I'm aware of have been addressed. Even things like blkid
misidentifing a disk as ext3 when it is added to a zfs pool. I'm
careful to always zero out the first 4k of any new zfs partition. That
all said this is all new code and while it looks like it's working right
for me we should keep an eye on it for any strange behavior.
Most of these fixes appear to be harmless and should never occur.
However, there were a few cases in this patch which do concern me,
I doubt we're seeing them but they look possible... mainly in the
user tools.