EMF_USE_MIP_MAPS was introduced in Irrlicht 1.8, don't use in 1.7.3 or below

This is not optimal as it will cause minor graphical glitches for
Irrlicht 1.7 users, but at least it fixes the build.

src/wieldmesh.cpp

@@ -290,7 +290,9 @@ void WieldMeshSceneNode::setExtruded(const std::string &imagename,
 		material.setFlag(video::EMF_TRILINEAR_FILTER, false);
 	}
 	// mipmaps cause "thin black line" artifacts
+#if (IRRLICHT_VERSION_MAJOR >= 1 && IRRLICHT_VERSION_MINOR >= 8) || IRRLICHT_VERSION_MAJOR >= 2
 	material.setFlag(video::EMF_USE_MIP_MAPS, false);
+#endif
 	if (m_enable_shaders) 
 		material.setTexture(2, tsrc->getTexture("disable_img.png"));
 }