Irrlicht: build against system libraries
Summary: Build Irrlicht against system libraries (namely libjpeg, libpng, libz and libbz2) instead of bundled libs.
Test Plan: Rebuilt minetest against this version and played Minetest Game and MineClone2 for a few minutes.
Reviewers: Triage Team, DataDrake
Reviewed By: Triage Team, DataDrake
Subscribers: DataDrake, ermo
Tags: Requires Rebuilds
Differential Revision: https://dev.getsol.us/D8877