Revert "GREML fit backend: Refactor code to remove inefficiency when analytic derivatives not in use."
Revert "GREML fit backend: Refactor code to remove inefficiency when analytic derivatives not in use."

This reverts commit a59c9328515986a60a7c868bcf0b38f8be551cd9.

jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx