Update to FreeBSD head 2017-06-01

Git mirror commit dfb26efac4ce9101dda240e94d9ab53f80a9e131.

Update #3472.

freebsd/sys/vm/uma_core.c

@@ -1980,6 +1980,9 @@ uma_zcreate(const char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
 	bool locked;
 #endif /* __rtems__ */
 
+	KASSERT(powerof2(align + 1), ("invalid zone alignment %d for \"%s\"",
+	    align, name));
+
 	/* This stuff is essential for the zone ctor */
 	memset(&args, 0, sizeof(args));
 	args.name = name;