'RELENG_6_0_0_RELEASE'.

This commit was manufactured to restore the state of the 6.0-RELEASE image.

signals instead of having more intricate knowledge of thread state
within signal handling.

Simplify signal code because of above (by David Xu).

Use macros for libpthread usage of pthread_cleanup_push() and
pthread_cleanup_pop().  This removes some instances of malloc()
and free() from the semaphore and pthread_once() implementations.

When single threaded and forking(), make sure that the current
thread's signal mask is inherited by the forked thread.

Use private mutexes for libc and libpthread.  Signals are
deferred while threads hold private mutexes.  This fix also
breaks www/linuxpluginwrapper; a patch that fixes it is at
http://people.freebsd.org/~deischen/kse/linuxpluginwrapper.diff

Fix race condition in condition variables where handling a
signal (pthread_kill() or kill()) may not see a wakeup
(pthread_cond_signal() or pthread_cond_broadcast()).

In collaboration with:	davidxu

a shared library or any other dyanmic allocated data block, once
pthread_once_t is initialized, a mutex is allocated, if we unload the
shared library or free those data block, then there is no way to deallocate
the mutex, result is memory leak.
To fix this problem, we don't use mutex field in pthread_once_t, instead,
we use its state field and an internal mutex and conditional variable in
libkse to do any synchronization, we introduce a third state IN_PROGRESS to
wait if another thread is already in invoking init_routine().
Also while I am here, make pthread_once() conformed to pthread cancellation
point specification.

Reviewed by: deischen

environment.  This includes support for multiple KSEs and KSEGs.

The ability to create more than 1 KSE via pthread_setconcurrency()
is in the works as well as support for PTHREAD_SCOPE_SYSTEM threads.
Those should come shortly.

There are still some known issues which davidxu and I are working
on, but it'll make it easier for us by committing what we have.

This library now passes all of the ACE tests that libc_r passes
with the exception of one.  It also seems to work OK with KDE
including konqueror, kwrite, etc.  I haven't been able to get
mozilla to run due to lack of java plugin, so I'd be interested
to see how it works with that.

Reviewed by:	davidxu

The new libpthread will provide POSIX threading support using KSE.
These files were previously repo-copied from src/lib/libc_r.

Reviewed by:	deischen
Approved by:	-arch

instead of #pragma weak to create weak definitions.

Suggested by:	bde

	_foo - wrapped system call
	foo - weak definition to _foo

and for cancellation points:

	_foo - wrapped system call
	__foo - enter cancellation point, call _foo(), leave
	        cancellation point
	foo - weak definition to __foo

Change use of global _thread_run to call a function to get the
currently running thread.

Make all pthread_foo functions weak definitions to _pthread_foo,
where _pthread_foo is the implementation.  This allows an application
to provide its own pthread functions.

Provide slightly different versions of pthread_mutex_lock and
pthread_mutex_init so that we can tell the difference between
a libc mutex and an application mutex.  Threads holding mutexes
internal to libc should never be allowed to exit, call signal
handlers, or cancel.

Approved by:	-arch

This fixes a segfault in some C++ programs which use exceptions before
main() has been called (i.e. from global constructors).

Reviewed by: deischen

Fix copyrights (s/REGENTS/AUTHOR).

Suggested by:	tg
Approved by:	jb