*: use void * for printing pointers

On higher warning levels, compilers expect %p printf arguments to be
void *.  Since format string / argument warnings can be useful
otherwise, let's get rid of this noise by sprinkling casts to void *
over printf calls.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index e6a3660..00d766d 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -8235,7 +8235,7 @@
   struct community *com;
 
   com = (struct community *) backet->data;
-  vty_out (vty, "[%p] (%ld) %s%s", backet, com->refcnt,
+  vty_out (vty, "[%p] (%ld) %s%s", (void *)backet, com->refcnt,
 	   community_str (com), VTY_NEWLINE);
 }