Add a new per-group SUBPACKAGE option to bsd.man.mk.  When MANSPLITPKG
is enabled, this is forced to "-man", otherwise it defaults to empty
but can be overridden by the caller.

Use this in bsd.lib.mk to install library manpages in the -dev package
instead of the base package.  This is nearly always preferable, since
library manpages are usually in section 2 or 3 and are only relevant
to people with development packages installed.

For manpages which should be installed in the base package even for
libraries, add a new MANNODEV group in bsd.lib.mk.  Update existing
Makefiles to use this where appropriate.

MFC after:	3 days
Discussed with:	olce
Reviewed by:	olce
Sponsored by:	https://www.patreon.com/bsdivy
Differential Revision:	https://reviews.freebsd.org/D52832

The "mkmagic" program should be built with the host compiler.

Only use BTOOLSPATH if not building for host

Obtained from:	Juniper Networks, Inc.
Reviewed by:	sjg
Differential Revision:	https://reviews.freebsd.org/D44539

MFC after:	3 days

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

The default ones are install them to /usr/libdata/pkgconfig, and we can't
use this path for compat libraries, so we use /usr/lib<suffix>/pkgconfigi here.

Test Plan:	grep -rn libdir= ./usr/lib32/pkgconfig/*.pc
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D34939

Now the .pc ends up in the correct package (-dev)

Reviewed by:	bapt, emaste
Differential Revision:	https://reviews.freebsd.org/D29172
MFC after:      2 weeks

Reported by:	lwhsu
MFC after:	2 weeks
X-MFC-with:	r362258

MFC after:	2 weeks

MFC after:	2 weeks

libmagic only depend on mkmagic if not DIRDEPS_BUILD

libpmc fix -I for libpmcstat

local.dirdeps.mk be even more careful about adding gnu/lib/csu to DIRDEPS

Reviewed by:	bdrewery
Differential Revision:	https://reviews.freebsd.org/D22872