PTREL-400: fix build in x86_64
use %cmake macro in spec files, use LIB_INSTALL_DIR
for install path instead of hardcoded /lib

Change-Id: I44b6bb09e56c2956e78564fcc55e6f7406e22cee
Signed-off-by: Stephane Desneux <stephane.desneux@eurogiciel.fr>