make sure we link with readline from ports

Index: configure
--- configure.orig
+++ configure
@@ -12914,7 +12914,7 @@ ac_res=$ac_cv_search_readline
 if test "$ac_res" != no
 then :
   test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
-  READLINE_LIBS="-lreadline"
+  READLINE_LIBS="-lereadline"
 else $as_nop
   as_fn_error $? "libreadline library not found" "$LINENO" 5
 fi
