Import (currently failing) test of false-positive in portcheck:

when you have a PKG_ARCH=* port and, to avoid WANTLIBs (coming from
MODULES, for example) getting in package, specify WANTLIB-= (empty),
portcheck misses this and still warns about non-empty WANTLIB.

The fix to be comitted separately in the next commit.

tests/portcheck/t18/Makefile

@@ -0,0 +1,12 @@
+# $OpenBSD: Makefile,v 1.1.1.1 2016/03/28 15:36:17 zhuk Exp $
+#
+# Check silence in case of PKG_ARCH=* and WANTLIB-= (empty)
+
+COMMENT		= test 18
+DISTNAME	= test-18
+PKG_ARCH=	*
+
+WANTLIB =	c
+ WANTLIB-=
+
+.include <bsd.port.mk>

tests/portcheck/t18/pkg/PLIST

@@ -0,0 +1,2 @@
+@comment $OpenBSD: PLIST,v 1.1.1.1 2016/03/28 15:36:17 zhuk Exp $
+bin/test18