Make sure the value of MKCOMPATMODULES gets imported into sets.subr,

so that the "compatmodules" keyword is properly handled when creating
the set lists.  Fixes the build for evbppc.

distrib/sets/mkvars.mk

@@ -1,4 +1,4 @@
-# $NetBSD: mkvars.mk,v 1.5 2011/10/31 08:14:43 mrg Exp $
+# $NetBSD: mkvars.mk,v 1.6 2011/11/02 14:42:43 he Exp $
 
 MKEXTRAVARS= \
 	MACHINE \
@@ -13,6 +13,7 @@ MKEXTRAVARS= \
 	MKMANZ \
 	MKBFD \
 	MKCOMPAT \
+	MKCOMPATMODULES \
 	MKDYNAMICROOT \
 	MKMANPAGES \
 	MKXORG \