config(1): Fix test breakage

Now config(1) checks the content of $S/conf/Makefile.kern.inc.  Install it
into config(1) test directory to fix test.  Noticed by Martin Husemann.

distrib/sets/lists/tests/mi

@@ -1,4 +1,4 @@
-# $NetBSD: mi,v 1.603 2014/12/08 04:23:03 ozaki-r Exp $
+# $NetBSD: mi,v 1.604 2014/12/20 07:02:25 uebayasi Exp $
 #
 # Note: don't delete entries from here - mark them as "obsolete" instead.
 #
@@ -3410,6 +3410,7 @@
 ./usr/tests/usr.bin/config/support/arch/regress/conf/files.regress		tests-usr.bin-tests	atf
 ./usr/tests/usr.bin/config/support/arch/regress/conf/std.regress		tests-usr.bin-tests	atf
 ./usr/tests/usr.bin/config/support/conf		tests-usr.bin-tests
+./usr/tests/usr.bin/config/support/conf/Makefile.kern.inc	tests-usr.bin-tests	atf
 ./usr/tests/usr.bin/config/support/conf/files	tests-usr.bin-tests	atf
 ./usr/tests/usr.bin/config/t_config		tests-usr.bin-tests	atf
 ./usr/tests/usr.bin/cut				tests-usr.bin-tests

tests/usr.bin/config/support/conf/Makefile

@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.1 2012/03/17 16:33:12 jruoho Exp $
+# $NetBSD: Makefile,v 1.2 2014/12/20 07:02:25 uebayasi Exp $
 
 .include <bsd.own.mk>
 
@@ -6,7 +6,8 @@ TESTSDIR=	${TESTSBASE}/usr.bin/config
 ATFFILE=	no
 
 FILESDIR=	${TESTSDIR}/support/conf
-FILES=		files
+FILES=		Makefile.kern.inc \
+		files
 
 .include <bsd.test.mk>
 .include <bsd.files.mk>

tests/usr.bin/config/support/conf/Makefile.kern.inc

@@ -0,0 +1,4 @@
+#	$NetBSD: Makefile.kern.inc,v 1.1 2014/12/20 07:02:25 uebayasi Exp $
+
+build_kernel: .USE
+	XXX