Remove libdcadec from license list

We're not using that library anymore.

resources/misc/licenses.txt

@@ -167,7 +167,6 @@ Others:
   - qtwebengine: LGPL v3, or GPL v2 or later (http://doc.qt.io/qt-5/qtwebenginewidgets-index.html#license-information)
 - mpv: GPL v2 or later (https://github.com/mpv-player/mpv/blob/master/LICENSE)
   - FFmpeg: LGPL v2.1 or later (http://www.ffmpeg.org/legal.html)
-    - libdcadec: LCPL v2.1 or later (https://github.com/foo86/dcadec/blob/master/COPYING.LGPLv2.1)
     - bzip2: BSD-style (http://www.bzip.org)
   - libass: ISC (https://github.com/libass/libass/blob/master/COPYING)
     - freetype: GPL 2 or FreeType License (http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/docs/LICENSE.TXT)