demux_lavf: remove recently added author name from license header

This was added in 585f9ff42f by @bbarenblat (github handle). We
don't do this. This file alone probably has multiple dozen of authors (I
didn't count, but it has a history of 15 years). If everyone added their
names with each small change, this project would have giant lists of
contributing authors on every source file.

Neither copyright law nor any of the used licenses require listing
authors in the license header. Authorship is recorded in the git log.

So don't start with this, and remove this recent case to avoid setting a
precedent.

Some files still have an author in the header. These cases are
grandfathered, and usually are the actual authors of the original code.

demux/demux_lavf.c

@@ -1,6 +1,5 @@
 /*
  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
- * Copyright (C) 2018 Google LLC
  *
  * This file is part of mpv.
  *