[arch-general] Move from libjpeg-turbo to mozjpeg

[N30N]

Hi there,

Mozilla have made a fork of the libjpeg-turbo package called mozjpeg,
which features improved encoding:
https://blog.mozilla.org/research/2014/03/05/introducing-the-mozjpeg-project/

I'd like to propose making the switch. The "library configuration
defaults are the same as for libjpeg-turbo, in order to make transitions
as painless as possible". A PKGBUILD can be found on the AUR:
https://aur.archlinux.org/packages/mozjpeg/


Thanks for your consideration,
N30N.