libavcodec/proresdec.h: fix license header

This was somehow missed when relicensing the decoder to LGPL
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/proresdec.h

@@ -5,16 +5,16 @@
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
+ * Lesser General Public License for more details.
  *
- * You should have received a copy of the GNU General Public
+ * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */