don't list man pages twice

--HG--
branch : HEAD

man/Makefile.am

diff --git a/man/Makefile.am b/man/Makefile.am
index b6ab80c..6dc3b22 100644
--- a/man/Makefile.am
+++ b/man/Makefile.am
@@ -1,12 +1,11 @@
-man_MANS=\
-	zipcmp.1 \
-	zip_open.3
+man_MANS=${MAN1} ${MAN3}
 
 DISTCLEANFILES=${man_MANS}
 
-MANDOC=\
-	zipcmp.mdoc
-	zip_open.mdoc
+MAN1=	zipcmp.1
+MAN3=	zip_open.3
+
+MANDOC=${MAN1:.1=.mdoc} ${MAN3:.3=.mdoc}
 MAN=${MANDOC:.mdoc=.man}
 
 EXTRA_DIST=${MANDOC} ${MAN}