Minor bug fix to dSFMT interface.
Minor bug fix to dSFMT interface.

Correct for reinitialisation.  The array of PRNGs was being correctly
regenerated but the pointer to the next PRNG wasn't reset to the
beginning of the array.

ruthfranklin/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande