Ext4's typical GPT partition type not recognized

Ext4's typical GPT partition type not recognized

Adding additional entries to the efi conversion array will help prevent
the overwriting of the GPTs of disks with in-use file systems in more
cases. Most notably, this adds partition type 8300 "Linux filesystem"
(0FC63DAF-8483-4772-8E79-3D69D8477DE4), which is often used for ext4 and
btrfs, among others.

This commit itself does nothing to address the underlying problematic
behavior that check_slice() isn't called on partitions of an
unrecognized type, even when they contain a currently mounted file
system.

The additional entries were derived from these two resources:
https://en.wikipedia.org/wiki/GUID_Partition_Table
http://sourceforge.net/p/gptfdisk/code/ci/master/tree/parttypes.cc

Signed-off-by: ilovezfs <ilovezfs@icloud.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4016