Remove spin lock functions

This was not a particularly good idea in user space.

include/vlc_threads.h

@@ -411,80 +411,6 @@ static inline void vlc_cleanup_lock (void *lock)
 }
 #define mutex_cleanup_push( lock ) vlc_cleanup_push (vlc_cleanup_lock, lock)
 
-#if defined (_POSIX_SPIN_LOCKS) && ((_POSIX_SPIN_LOCKS - 0) > 0)
-typedef pthread_spinlock_t vlc_spinlock_t;
-
-/**
- * Initializes a spinlock.
- */
-static inline void vlc_spin_init (vlc_spinlock_t *spin)
-{
-    if (pthread_spin_init (spin, PTHREAD_PROCESS_PRIVATE))
-        abort ();
-}
-
-/**
- * Acquires a spinlock.
- */
-static inline void vlc_spin_lock (vlc_spinlock_t *spin)
-{
-    pthread_spin_lock (spin);
-}
-
-/**
- * Releases a spinlock.
- */
-static inline void vlc_spin_unlock (vlc_spinlock_t *spin)
-{
-    pthread_spin_unlock (spin);
-}
-
-/**
- * Deinitializes a spinlock.
- */
-static inline void vlc_spin_destroy (vlc_spinlock_t *spin)
-{
-    pthread_spin_destroy (spin);
-}
-
-#elif defined (WIN32)
-typedef CRITICAL_SECTION vlc_spinlock_t;
-
-static inline void vlc_spin_init (vlc_spinlock_t *spin)
-{
-    if (!InitializeCriticalSectionAndSpinCount(spin, 4000))
-        abort ();
-}
-
-static inline void vlc_spin_lock (vlc_spinlock_t *spin)
-{
-    EnterCriticalSection(spin);
-}
-
-static inline void vlc_spin_unlock (vlc_spinlock_t *spin)
-{
-    LeaveCriticalSection(spin);
-}
-
-static inline void vlc_spin_destroy (vlc_spinlock_t *spin)
-{
-    DeleteCriticalSection(spin);
-}
-
-#else
-/* Fallback to plain mutexes if spinlocks are not available */
-typedef vlc_mutex_t vlc_spinlock_t;
-
-static inline void vlc_spin_init (vlc_spinlock_t *spin)
-{
-    vlc_mutex_init (spin);
-}
-
-# define vlc_spin_lock    vlc_mutex_lock
-# define vlc_spin_unlock  vlc_mutex_unlock
-# define vlc_spin_destroy vlc_mutex_destroy
-#endif
-
 #ifdef __cplusplus
 /**
  * Helper C++ class to lock a mutex.