Some improvements to *_l.3 manual pages (all part of 1003.1-2008).

* Fix the SYNOPSIS to show that for these functions, <xlocale.h> need
  not be included.

* Better markup for the locale argument.

* Additional mentioning of the *_l() function in descriptions, return
  value, etc.
mdocml: fix .Fo/.Fa output

`mandiff' differences reduced from 2686 to 2575.
mdocml: adjust libbluetooth name
zic.8: Fix section in .Xr macro.
mdocml: mark lib.in as locally modified

DragonFly, FreeBSD, and groff all disagree on the name of
libbluetooth.  Treat the previous commit as a DragonFly
modification then.  Thanks to Ingo Schwarze for pointing
out this fact.