Remove bio_cachep from slab.h

bio_cachep is no longer used it seems.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.19-rc5-mm2/include/linux/slab.h
===================================================================
--- linux-2.6.19-rc5-mm2.orig/include/linux/slab.h	2006-11-21 14:11:29.000000000 -0600
+++ linux-2.6.19-rc5-mm2/include/linux/slab.h	2006-11-21 14:11:50.892581249 -0600
@@ -303,7 +303,6 @@ extern kmem_cache_t	*files_cachep;
 extern kmem_cache_t	*filp_cachep;
 extern kmem_cache_t	*fs_cachep;
 extern kmem_cache_t	*sighand_cachep;
-extern kmem_cache_t	*bio_cachep;
 
 #endif	/* __KERNEL__ */