version namespace which was needed before the library version was
bumped.

(part of libc) can use pthreads mutexes without causing infinite recursion
during initialization.

used LIBTHREAD_1_0 as its version definition, but now needs
to define its symbols in the same namespace used by libc.
The compatibility hooks allows you to use libraries and
binaries built and linked to libpthread before libc was
built with symbol versioning.  The shims can be removed if
libpthread is given a version bump.

Reviewed by:	davidxu

is defined in the environment.

Requested by:	jmg & a few others

The thread jump table has been resorted, so you need to
keep libc, libpthread, and libthr in sync.

Submitted by:	xu

o  Don't reinitialise the atfork() handler list in the child.  We
   are meant to call the child handler, and on subsequent fork()s
   should call all three functions as normal.
o  Don't reinitialise the thread specific keyed data in the
   child after a fork.  Applications may require this for context.
o  Reinitialise curthread->tlflags after removing ourselves from
   (and reinitialising) the various internal thread lists.
o  Reinitialise __malloc_lock in the child after fork() (to balance
   our explicitly taking the lock prior to the fork()).

With these changes, it is possible to enable the NOTYET code in
thr_kern.c to allow the use of non-async-safe functions after
fork()ing from a threaded program.

Reviewed by:	Daniel Eischen <deischen@freebsd.org>
[_malloc_lock reinitialisation has since been moved to avoid polluting the
!NOTYET code]

changed to use the statclock.  Make sure we calculate the value
of a tick correctly in userland.

Noticed by:	Kazuaki Oda <kaakun at highway dot ne dot jp>

attribute when the library is initialized.