Declare error integer to be standard integer rather than int_p.
Declare error integer to be standard integer rather than int_p.

This is required for MPI compilation with POP_SIZE=64.  Easy to slip
through...

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