EXTRA_DIST was already defined in this one

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@1596 e5f2f494-b856-4b98-b285-d166d9295462

src/bin/loadzone/Makefile.am

@@ -22,7 +22,7 @@ install-data-local:
 	$(mkinstalldirs) $(DESTDIR)/@localstatedir@/@PACKAGE@
 # TODO: permissions handled later
 
-EXTRA_DIST =  testdata/README
+EXTRA_DIST += testdata/README
 EXTRA_DIST += testdata/dsset-subzone.example.com.
 EXTRA_DIST += testdata/example.com
 EXTRA_DIST += testdata/example.com.signed