* thread.cc (pthread_rwlock::add_reader): Remove mx parameter for

* thread.cc (pthread_rwlock::add_reader): Remove mx parameter for
List_insert call.
(pthread::prepare): Ensure race safeness when adding function
pointers to atfork lists by using List_insert.
* thread.h (List_insert): Use InterlockedCompareExchangePointer to
ensure race safeness without using a mutex.
(List_remove): Use InterlockedCompareExchangePointer to
ensure race safeness with List_insert.
(List::insert): Remove mx parameter for	List_insert call.