flann: Fix update macro and download URL

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
ffmpeg: Update

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
cairo: Update

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
config.guess: Update

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
armadillo: Update

Signed-off-by: Timothy Gu <timothygu99@gmail.com>