Make the instance lock static

(it's not distinct from the module bank lock)

src/libvlc.c

@@ -228,7 +228,7 @@ static int  VerboseCallback( vlc_object_t *, char const *,
 
 static void InitDeviceValues( libvlc_int_t * );
 
-vlc_mutex_t global_lock = VLC_STATIC_MUTEX;
+static vlc_mutex_t global_lock = VLC_STATIC_MUTEX;
 
 /**
  * Allocate a libvlc instance, initialize global data if needed

src/libvlc.h

@@ -45,7 +45,6 @@ void system_End       ( libvlc_int_t * );
 /*
  * Threads subsystem
  */
-extern vlc_mutex_t global_lock; /* TODO: remove this crap */
 
 /* Hopefully, no need to export this. There is a new thread API instead. */
 void vlc_thread_cancel (vlc_object_t *);