We change the search procedure so it detects NixOS from /etc/os-release
and uses "libnuma.so" when calling dlopen, instead of harcoding a full
path to /usr. The full patch of libnuma is stored in the runpath, so
dlopen can find it.
Reviewed-by: Aleix Boné <abonerib@bsc.es>
Tested-by: Vincent Arcila <vincent.arcila@bsc.es>
