[aur-general] Remove i3lock-libcairo

[Robert Knauer]

Hi,
the community/i3lock package is since version 2.4-2 compiled with image 
support, so my package i3lock-libcairo [1] isn't necessary anymore and you can 
delete it.

Thanks.

[1] https://aur.archlinux.org/packages.php?ID=50985