games/scummvm: Update to 2.8.0

• Add new default option MIKMOD, which adds support for Impulse Tracker audio files that are used by some games of the "ags" engine.

• Introduce the non-default options SONIVOX and VPX as well. The latter one adds movie support for the "sludge" engine which is still considered as unstable and therefore not built by default.

• Add a workaround make the "xeen" engine, which could be built by default since release 2.5.0, still available and remove a no longer required patch for the "hpl" engine.

Changelog:

https://downloads.scummvm.org/frs/scummvm/2.8.0/ReleaseNotes.html

MFH: No (feature release)