**HACKS** to make ports tree use libc-iconv.  These are samples,
you're on your own.

Index: Mk/Uses/iconv.mk
===================================================================
--- Mk/Uses/iconv.mk	(revision 322973)
+++ Mk/Uses/iconv.mk	(working copy)
@@ -16,6 +16,6 @@
 IGNORE=	USES=iconv does not require args
 .endif
 
-LIB_DEPENDS+=	iconv.3:${PORTSDIR}/converters/libiconv
+#LIB_DEPENDS+=	iconv.3:${PORTSDIR}/converters/libiconv
 
 .endif
Index: archivers/unzip/Makefile
===================================================================
--- archivers/unzip/Makefile	(revision 322973)
+++ archivers/unzip/Makefile	(working copy)
@@ -48,7 +48,7 @@
 PATCH_DIST_STRIP+=	-p1
 USES=			iconv
 CFLAGS+=		-I${LOCALBASE}/include -DNATIVE
-MAKE_ARGS+=		LFLAGS1="-L${LOCALBASE}/lib -liconv"
+#MAKE_ARGS+=		LFLAGS1="-L${LOCALBASE}/lib -liconv"
 .endif
 
 MAKE_ENV=	LOCAL_UNZIP="${LOCAL_UNZIP}" \
Index: devel/glib20/Makefile
===================================================================
--- devel/glib20/Makefile	(revision 322973)
+++ devel/glib20/Makefile	(working copy)
@@ -32,7 +32,7 @@
 MAKE_JOBS_SAFE=	yes
 USE_PYTHON=	2.5+
 USE_PERL5=	yes
-CONFIGURE_ARGS=	--enable-static --with-libiconv=gnu \
+CONFIGURE_ARGS=	--enable-static --with-iconv=yes \
 		--disable-gtk-doc --with-html-dir=${PREFIX}/share/doc \
 		--disable-man --without-xml-catalog \
 		--with-pcre=system \
Index: lang/php5/Makefile.ext
===================================================================
--- lang/php5/Makefile.ext	(revision 324376)
+++ lang/php5/Makefile.ext	(working copy)
@@ -126,7 +126,7 @@
 .endif

 .if ${PHP_MODNAME} == "iconv"
-CONFIGURE_ARGS+=--with-iconv=${LOCALBASE}
+#CONFIGURE_ARGS+=--with-iconv=${LOCALBASE}

 USES+=	iconv
 .endif