Some users copy libxran.so to a system directory (e.g., /usr/local/lib).
At the same time, we require xran_LOCATION to be set to find the build
directory. Use HINTS to prefer the location passed through
xran_LOCATION.
Also, use NO_DEFAULT_PATH to outright disallow global scope, to prevent
"accidentally" finding libxran.so in global scope (this is for
multi-user systems that are used in development, and where people have
different version of libxran for testing purposes). To still use
packages in e.g., /usr/local/, it would be possible to set xran_LOCATION
to this directory. (there is a problem that the version information will
likely not be read correctly, so this might not be enough)