Quick hack: add $wgMaxAnimatedGifArea so we don't try to render animated thumbs for...

Quick hack: add $wgMaxAnimatedGifArea so we don't try to render animated thumbs for huge animated GIFs.
'Tugra Mahmuds II Big Size.gif' on Commons otherwise seems to eat as much CPU and memory as you can throw at it (1,876 × 1,500 pixel, file size: 4.36 MB, MIME type: image/gif)