Zero local_estimators array before use.
Zero local_estimators array before use.

(Presumably this once was estimatators, which was (unnecssarily) zeroed,
before the addition of MPI...)  Fixes bug introduced in master in
7c532fa60e, where NaNs were returned for canonical HF energy
calculations with some compilers.

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