try to force tar to not use iconv

openpkg/openpkg.spec

@@ -310,6 +310,7 @@ Provides:     OpenPKG
   
     #   build GNU tar tool
     ( cd tar-%{V_tar}
+      echo 'am_cv_func_iconv=${am_cv_func_iconv=no}' >config.cache
       CC="${l_cc}" 
       ./configure \
           --prefix=%{l_prefix} \