Add configuration options to override physical and UNMAP blocks geometry.

While in most cases CTL should correctly fetch those values from backing
storages, there are some initiators (like MS SQL), that may not like large
physical block sizes, even if they are true.  For such cases allow override
fetched values with supported ones (like 4K).

MFC after:	1 week
Parallelize building gnu/usr.bin/groff

This speeds up building the directory from the bootstrap-tools stage in
buildworld as well as building from the subdirectory

Based on a patch submitted via -arch:
https://lists.freebsd.org/pipermail/freebsd-arch/2014-December/016493.html

MFC after: 1 week
Submitted by: Jia-Shiun Li <jiashiun@gmail.com>
Sponsored by: EMC / Isilon Storage Division
Fix sporadic build failures due to race when running make installworld
when strip gets replaced at install time by adding it to ITOOLS for the
default usr.bin/xinstall STRIP_CMD

This will fix the failure noted in this Jenkins build step:
https://jenkins.freebsd.org/job/Build-UFS-image/688/

This will also fix the issue reported by alfred@ dealing with installing on
targets that differ from build hosts (e.g. installing on i386/i386 when built
on amd64/amd64)

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division
Plug a memory leak in an error code path.

Reported by:	Coverity
CID:		1018936
MFC after: 	3 days
Add a missing break.

Reported by:	Coverity
CID:		1232014
MFC after: 	3 days
Use the correct macro for listing the maximum bus space size.

Without this, it fails to compile on i386 PAE builds.
Update the use of bus space macros to be more correct.

This was a problem on i386 PAE builds.