treatment of 'LIBKSE' as an "old style" knob.

Submitted by:	ru
Approved by:	re(kensmith)

This introduces the WITHOUT_LIBKSE nob,
and changes WITHOUT_LIBPTHREADS to mean with neither threading libs.
Approved by:	re(kensmith)

the threading libraries is built.  This simplifies the
logic in makefiles that need to check if the pthreads
support is present.  It also fixes a bug where we would
build a threading library that we shouldn't have built:
for example, building with WITHOUT_LIBTHR and the default
value of DEFAULT_THREADING_LIB (libthr) would mistakenly
build the libthr library, but not install it.

Approved by:	re (kensmith)

- Don't build ngctl(8) and cached(8) if threading libs aren't built.
- Fix various issues in a cached(8) makefile.

is (sym)linked to libpthread.  Account for this change and
check for MK_LIBTHR instead of MK_LIBC_R where appropriate.

on platform.

http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

The src.conf(5) manpage is to follow in a few days.

Brought to you by:	imp, jhb, kris, phk, ru (all bugs are mine)

Reported by:	Andrea Campi <andrea+freebsd_cvs_all@webcom.it>
Approved by:	re (scottl)