Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Fix the code that matches userids in match_jobspec(). It needs to check
the username-for-accounting field (P), not the username-for-headerpage (L).
These are usually the same value, except that control files do not have
the username-for-headerpage field if the user has requested no header page.
- Also rename the cji_username field to cji_headruser, to make it clear that
the value should only be used for the header page. (aka banner page)

MFC after: 3 weeks

Take advantage of the common_source/lp.cdefs.h file to change lpr
source to use __FBSDID() for setting rcsids. Also fix the format
of 'sccsid' lines to consistently match style(9) guidelines.

Reviewed by: discussed with bde and obrien
MFC after: 15 days

Move prototypes for ctl_readcf and ctl_freeinf from ctlinfo.c to ctlinfo.h,
so the routines can be called by an upcoming change for 'lpc topq/bottomq'.

MFC after: 3 days

Change lpd to perform sanity and safety checks on control files as it
receives them from other hosts. This is meant to protect from both
nefarious users (which maybe broke into some remote host that we accept
print jobs from), and broken implementations of lpr on other platforms.
This is done by changing recvjob.c to call the new ctl_renametf()
routine in the new common_source/ctlinfo.[ch] files. This will not
affect jobs coming via lpr on the local machine.

Reviewed by: freebsd-print@bostonradio.org & freebsd-audit
MFC after: 16 days