Remove conditional when calculating walker_data for dmqmc.
Remove conditional when calculating walker_data for dmqmc.

walker_data(1,k) should store 0.5*(H_ii + H_jj) so that it
can be used in the death/cloning step as well as for evaluating
the energy on the zero excitation-level density matrix elements.

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