another distclean fix

Signed-off-by: Thorsten Glaser <tg@mirbsd.org>

mk/build.mk

@@ -214,7 +214,9 @@ distclean:
 
 else # ! ifeq ($(strip $(ADK_HAVE_DOT_CONFIG)),y)
 
-ifneq ($(filter-out distclean,${MAKECMDGOALS}),)
+ifeq ($(filter-out distclean,${MAKECMDGOALS}),)
+include ${TOPDIR}/mk/vars.mk
+else
 include $(TOPDIR)/prereq.mk
 export BASH HOSTCC HOSTCFLAGS MAKE LANGUAGE LC_ALL OStype PATH
 endif