MFC r247281:

Add i/o error counters to hastd(8) and make hastctl(8) display
them.  This may be useful for detecting problems with HAST disks.

Discussed with and reviewed by: pjd
MFC r247281, r247345:

r247281:

Add i/o error counters to hastd(8) and make hastctl(8) display
them.  This may be useful for detecting problems with HAST disks.

Discussed with and reviewed by: pjd

r247345:

Fix casting.