Update cmake code to find Irrlicht so that it matches what unit_IRRLICHT uses to find Irrlicht
Update cmake code to find Irrlicht so that it matches what unit_IRRLICHT uses to find Irrlicht

andrewseidl/chrono,andrewseidl/chrono,amelmquist/chrono,amelmquist/chrono,jcmadsen/chrono,projectchrono/chrono,armanpazouki/chrono,Bryan-Peterson/chrono,projectchrono/chrono,armanpazouki/chrono,dariomangoni/chrono,PedroTrujilloV/chrono,tjolsen/chrono,dariomangoni/chrono,jcmadsen/chrono,dariomangoni/chrono,dariomangoni/chrono,armanpazouki/chrono,jcmadsen/chrono,amelmquist/chrono,rserban/chrono,projectchrono/chrono,projectchrono/chrono,projectchrono/chrono,hsu/chrono,Bryan-Peterson/chrono,jcmadsen/chrono,rserban/chrono,tjolsen/chrono,rserban/chrono,hsu/chrono,Bryan-Peterson/chrono,tjolsen/chrono,PedroTrujilloV/chrono,armanpazouki/chrono,tjolsen/chrono,rserban/chrono,andrewseidl/chrono,Milad-Rakhsha/chrono,PedroTrujilloV/chrono,hsu/chrono,armanpazouki/chrono,hsu/chrono,hsu/chrono,andrewseidl/chrono,jcmadsen/chrono,jcmadsen/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,Bryan-Peterson/chrono,jcmadsen/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,amelmquist/chrono,andrewseidl/chrono,dariomangoni/chrono,PedroTrujilloV/chrono,Bryan-Peterson/chrono,tjolsen/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,Milad-Rakhsha/chrono,rserban/chrono,rserban/chrono,PedroTrujilloV/chrono,amelmquist/chrono,rserban/chrono,armanpazouki/chrono