Fork is carrying around a reverted commit

[connorjward]

For some time this PETSc fork has included an extra commit required for Firedrake to work. This commit removes the following code from fieldsplit.c:

          {
            PetscErrorCode (*func)(KSP,Mat,Mat,void*);
            void            *ctx;

            ierr = DMKSPGetComputeOperators(pc->dm, &func, &ctx);CHKERRQ(ierr);
            ierr = DMKSPSetComputeOperators(dms[i],  func,  ctx);CHKERRQ(ierr);
          }

This is due to an unresolved upstream issue.

See also:

• https://gitlab.com/petsc/petsc/-/issues/575 (related issue)
• https://gitlab.com/petsc/petsc/-/merge_requests/2171 (attempt to fix)

It would be good to fix this upstream. This fork could then simply mirror PETSc main.