x86/h263_loopfilter: Fix author attribution after code has been moved/splited around

Reference:
    commit 3615e2be84
    Author: Michael Niedermayer <michaelni@gmx.at>
    Date:   Tue Dec 2 22:02:57 2003 +0000

        h263_h_loop_filter_mmx

        Originally committed as revision 2553 to svn://svn.ffmpeg.org/ffmpeg/trunk

    commit 359f98ded9
    Author: Michael Niedermayer <michaelni@gmx.at>
    Date:   Tue Dec 2 20:28:10 2003 +0000

        h263_v_loop_filter_mmx

        Originally committed as revision 2552 to svn://svn.ffmpeg.org/ffmpeg/trunk
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/x86/h263_loopfilter.asm

@@ -1,20 +1,22 @@
 ;******************************************************************************
 ;* MMX-optimized H.263 loop filter
+;* Copyright (c) 2003-2013 Michael Niedermayer
+;* Copyright (c) 2013 Daniel Kang
 ;*
-;* This file is part of Libav.
+;* This file is part of FFmpeg.
 ;*
-;* Libav is free software; you can redistribute it and/or
+;* FFmpeg is free software; you can redistribute it and/or
 ;* 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.
 ;*
-;* Libav is distributed in the hope that it will be useful,
+;* 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
 ;* Lesser General Public License for more details.
 ;*
 ;* You should have received a copy of the GNU Lesser General Public
-;* License along with Libav; if not, write to the Free Software
+;* License along with FFmpeg; if not, write to the Free Software
 ;* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 ;******************************************************************************