Bump __FreeBSD_version to reflect 6.4 now that the branching has been done for 6.4.
Bump __FreeBSD_version to reflect 6.4 now that the branching has been
done for 6.4.

Approved by:	re (implicit)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase