The C preprocessor symbol WITH_NUMA is never defined. Instead, the symbol
HAVE_LIBNUMA is used for checking if the feature is to be used.

If cmake -DWITH_NUMA=OFF is specified, HAVE_LIBNUMA will not be defined
at compilation time even if the library is available.

If cmake -DWITH_NUMA=ON is specified but the library is not available
at configuration time, the compilation will be aborted.