Fix (struct vpi_ii).p type

It needs to be a generic pointer pointer, because it is initialized as
a pointer to a pointer to an arbitrary struct, yet (void **) is can not
be dereferenced.

Right now, the instance info is not used, but this might change.

include/vcc_interface.h

@@ -75,7 +75,7 @@ void VPI_acl_log(VRT_CTX, const char *);
 
 /* vmod object instance info */
 struct vpi_ii {
-	const void *			p;
+	uintptr_t *			p;
 	const char * const		name;
 };