Use GNU readline as our base readline lacks add_history_time().

Index: configure
--- configure.orig
+++ configure
@@ -55428,7 +55428,7 @@ fi
 	fi
         readline_ld_flags="-L$readline_prefix/lib"
         if test -z "$readline_lib_flags"; then
-            readline_lib_flags="-lreadline"
+            readline_lib_flags="-lereadline"
         fi
         run_readline_test="yes"
     elif test "$readline_requested" = "yes"; then