Any reason to continue linking these libs? libmng provides support for loading MNGs (animated PNGs) but MNG is essentially a dead format at this point and T3D never fully supported it anyway. The engine is also linking against a very old version of the lib (from 2007 I think?) which isn't good. lungif is intended for loading GIFs but again, the engine is linking against a very old version of the library and doesn't really support animated GIFs anyway.