There hasn't been a use for lll_unlock_wake_cb since it was
removed globally in 2007-05-29. This patch removes the
function from hppa's lowlevellock.[ch] implementation.
Updates the hppa-specific pthread.h from the generic version.
After this update the only difference between the generic
version and the hppa version is the footer protected by the
_PTHREAD_H_HPPA_ guard.