interrupt() / notify() fix.

interrupt() / notify() fix.

* src/threads/native/lock.c (lock_record_wait, lock_record_notify):
Correctly handling the signaled and interrupted flags.

* src/threads/native/threads.c (threads_wait_with_timeout)
(threads_wait_with_timeout_relative): No return value, not touching flags.
(threads_check_if_interrupted_and_reset): Now locking the waitmutex.
(threads_sleep): Adapted to change.

* src/threads/native/threads.h (threads_wait_with_timeout_relative): No
return value.