luajit_2.0.0.bb: Fix regexpt to change hardcodes path to fix rebuilds

when rebuilding we were running into issues where /usr/lib64 was
being made /usr/lib6464 and install was failing. Now we check if /lib
is at the end of line then only we replace it.

Fixes the reinstall issue

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>