fix a bug in printing log of similarity matrix.
fix a bug in printing log of similarity matrix.

if declare the row num as int type, and multiply it by itself,
it might lead to overflow problem.
now it is revised to uint64_t type.

pombredanne/idmlib,pombredanne/idmlib,izenecloud/idmlib,pombredanne/idmlib,pombredanne/idmlib,izenecloud/idmlib,izenecloud/idmlib,izenecloud/idmlib,izenecloud/idmlib