Add /usr/lib64 and /usr/lib directory hints to cmake module libassimp.so library installs in /usr/lib for 32bit or in /usr/lib64 for 64bit distros. All linux distros apply custom patch to extend cmake HINTs to systems /usr/lib and /usr/lib64 (see https://gitweb.gentoo.org/repo/gentoo.git/tree/media-libs/assimp/files/findassimp-3.3.1.patch) Signed-off-by: Maksym Sditanov <msditanov@200volts.com>