lavfutils: fix copyright

git blame:
     77 Stefano Sabatini
      1 Michael Niedermayer

Initial commit:
commit 2f83681c
Author: Stefano Sabatini <stefasab@gmail.com>
Date:   Sat Mar 10 14:01:28 2012 +0100

    lavfi: port libmpcodecs remove-logo filter

    The code is based on the remove-logo filter in MPlayer/libmpcodecs, by
    Robert Edele, relicensed to LGPL with consent of the author.

    Address trac issue #249.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>