Two fixes in renderpipe...

- Renderwin still used a thread-unsafe malloc, in the header text print

- Setting clipping flags in vertices for parts required a mutex lock after
  all... I thought it would go fine, but noticed on renders with small
  amounts of faces that sometimes faces disappear from a render.
  (was doing movie credits, so all faces are visible! Otherwise it would
  have hardly been noticable...)

source/blender/blenlib/BLI_threads.h

@@ -31,6 +31,10 @@
 #ifndef BLI_THREADS_H
 #define BLI_THREADS_H 
 
+/* default lock is to protect MEM_ module calls, one custom lock available now. van be extended */
+#define LOCK_MALLOC		0
+#define LOCK_CUSTOM1	1
+
 
 void	BLI_init_threads	(ListBase *threadbase, void *(*do_thread)(void *), int tot);
 int		BLI_available_threads(ListBase *threadbase);
@@ -39,8 +43,8 @@ void	BLI_insert_thread	(ListBase *threadbase, void *callerdata);
 void	BLI_remove_thread	(ListBase *threadbase, void *callerdata);
 void	BLI_end_threads		(ListBase *threadbase);
 
-void	BLI_lock_thread		(void);
-void	BLI_unlock_thread	(void);
+void	BLI_lock_thread		(int type);
+void	BLI_unlock_thread	(int type);
 
 		/* threadsafe version of MEM_malloc and friends */
 void	*MEM_mallocT(int len, char *name);