make -liconv dependency available thru pkg-config

fontconfig/fontconfig.spec

@@ -75,9 +75,9 @@ AutoReqProv:  no
         -e 's;/usr/lib/X11;;g' \
         configure
 
-    #   add freetype and expat dependencies
+    #   add iconv, freetype and expat dependencies
     %{l_shtool} subst \
-        -e '/^Libs:/s;$; -lfreetype -lexpat;' \
+        -e '/^Libs:/s;$; -liconv -lfreetype -lexpat;' \
         fontconfig.pc.in
 
     CC="%{l_cc}" \