[Tuples] Creating a GIMPLE_MODIFY_STMT unnecessary for gimplify_omp_for

[Andrew Pinski]

Hi,
  When I was comparing the tuples branch to the trunk, I noticed that
inside gimplify_omp_for, we call build_gimple_modify_stmt and then
fall through to GIMPLE_MODIFY_STMT but really we don't need it.  I
have not tested removing it but I thought I would send out what I
found while reviewing gimplify.c.

Thanks,
Andrew Pinski