* lib/windows-mutex.h: New file, extracted from lib/glthread/lock.h.
* lib/windows-mutex.c: New file, extracted from lib/glthread/lock.c.
* lib/windows-spinlock.h: New file, extracted from lib/glthread/lock.h.
* lib/glthread/lock.h: Include windows-spinlock.h, windows-mutex.h.
(gl_spinlock_t): Remove type.
(gl_lock_t): Define using glwthread_mutex_t.
(gl_lock_initializer): Define using GLWTHREAD_MUTEX_INIT.
(glthread_lock_init): Define using glwthread_mutex_init.
(glthread_lock_lock): Define using glwthread_mutex_lock.
(glthread_lock_unlock): Define using glwthread_mutex_unlock.
(glthread_lock_destroy): Define using glwthread_mutex_destroy.
(glthread_lock_init_func, glthread_lock_lock_func,
glthread_lock_unlock_func, glthread_lock_destroy_func): Remove
declarations.
Use glwthread_spinlock_t instead of gl_spinlock_t.
(gl_rwlock_initializer, gl_recursive_lock_initializer): Define using
GLWTHREAD_SPINLOCK_INIT.
* lib/glthread/lock.c (glthread_lock_init_func, glthread_lock_lock_func,
glthread_lock_unlock_func, glthread_lock_destroy_func): Remove
functions.
* lib/glthread/cond.h: Use glwthread_spinlock_t instead of
gl_spinlock_t.
* modules/windows-mutex: New file.
* modules/lock (Depends-on): Add windows-mutex.