SDL libraries reorganization

[felixaszx]

From Arch Linux: https://archlinux.org/packages/?sort=&q=sdl&maintainer=&flagged=
They have replaced all old SDL libraries with -compat libraries base on later version of SDL. Additionally unify namings for SDL (at least figure out when to use lower/upper case letters) should also be reconsidered in our repo.

[felixaszx]

This will trigger lots of rebuilds, hence I would like to gather some advices before proceed to the next stage....