[gnuplot] Removed conf file fixing libgd autodetection

Note: libgd is need for being able to export png, jpeg and gif files!
      Of course libgd needs to be compiled with the proper support for the
      mentioned formats relying on 3rd. party libs like libpng and libjpeg.

scientific/gnuplot/gnuplot.conf

@@ -1,16 +0,0 @@
-# --- SDE-COPYRIGHT-NOTE-BEGIN ---
-# This copyright note is auto-generated by ./scripts/Create-CopyPatch.
-#
-# Filename: package/.../gnuplot/gnuplot.conf
-# Copyright (C) 2004 - 2006 The T2 SDE Project
-# Copyright (C) 1998 - 2003 Clifford Wolf
-#
-# More information can be found in the files COPYING and README.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; version 2 of the License. A copy of the
-# GNU General Public License can be found in the file COPYING.
-# --- SDE-COPYRIGHT-NOTE-END ---
-
-confopt="$confopt --with-readline=gnu --without-gd"