* thread.cc (MTinterface::fixup_after_fork): Fix thread list after fork.

* thread.cc (MTinterface::fixup_after_fork): Fix thread list after fork.
(pthread::threads): Instantiate.
(pthread::pthread): Initialize running and suspendend.
Initialize next with NULL.
Add thread to thread list if it is not the null_pthread.
(pthread::~pthread): Remove thread from thread list if it is not the null_pthread.
(pthread::postcreate): Set running flag.
(pthread::exit): Reset running flag.
(pthread::cancel): Try to cancel thread only if still running.
(pthread::_fixup_after_fork): Implement.
(pthread::detach): Check if thread is still running before detach.
* thread.h (pthread::running): New member.
(pthread::next): Ditto.
(pthread::fixup_after_fork): New static method.
(pthread::threads): New static method.
(pthread::_fixup_after_fork): New method.