Mechanically convert to if_inc_counter().
Add dtrace probe support for zfs SET_ERROR(..)

MFC after:	1 week
Sponsored by:	Multiplay
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().