* lib/pthread.in.h: Define replacement functions only if GNULIB_PTHREAD
is 1.
* m4/pthread_h.m4: Renamed from m4/pthread.m4.
(gl_PTHREAD_H): Renamed from gl_PTHREAD_CHECK. Don't test whether
<pthread.h> pollutes the namespace; instead, prepare for generating a
pthread.h always. Substitute HAVE_PTHREAD_H here.
(gl_PTHREAD_H_DEFAULTS): Renamed from gl_PTHREAD_DEFAULTS. Initialize
GNULIB_PTHREAD. Don't initialize HAVE_PTHREAD_H here.
* modules/pthread-h: New file, based on modules/pthread.
* modules/pthread: Rely on 'pthread-h'.
* m4/pthread_mutex_timedlock.m4 (gl_FUNC_PTHREAD_MUTEX_TIMEDLOCK):
Update.
* modules/pthread_mutex_timedlock (Depends-on): Add pthread-h. Remove
pthread.