Disable libavif dependency for Android builds
Building the dependencies of libavif fails for Android builds because the Perl module xml-parser is linked to the target expat instead of the host expat.
See for example https://invent.kde.org/graphics/okular/-/jobs/1535063#L748 which is the first build of okular release/23.08 pulling in libavif.
Edited by Ingo Klöcker