Update checksum of libvpx

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Fix libnut/ffmpeg compilation on i686-pc-mingw32

Fixes #255.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Merge pull request #258 from TimothyGu/emerg

Fix libnut/ffmpeg compilation on i686-pc-mingw32