sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

GEOM: Reduce unnecessary log interleaving with sbufs

Similar to what was done for device_printfs in r347229.

Convert g_print_bio() to a thin shim around g_format_bio(), which acts on an
sbuf; documented in g_bio.9.

Reviewed by: markj
Discussed with: rlibby
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D21165