Add GET LBA STATUS command support to CTL.

It is implemented for LUNs backed by ZVOLs in "dev" mode and files.
GEOM has no such API, so for LUNs backed by raw devices all LBAs will
be reported as mapped/unknown.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Decode some binary fields of Intel metadata.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after:	2 weeks
Fix a 20+ year bug by using an appropriate constant for
the transition from one asymptotic approximation to another
for the zeroth order Bessel and Neumann functions.

Reviewed by:	bde