There was originally no way from an actual argument to get
to the corresponding dummy argument, even if the job of sorting
and matching actual with dummy arguments was done.
The closest was a field named actual in gfc_intrinsic_arg that was
used as scratch data when sorting arguments of one specific call.
However that value was overwritten later on as arguments of another
call to the same procedure were sorted and matched.

This change removes that field and adds instead a new field
associated_dummy in gfc_actual_arglist.  This field uses the just
introduced gfc_dummy_arg interface, which makes it usable with
both external and intrinsic procedure dummy arguments.

As the removed field was used in the code sorting and matching arguments,
that code has to be updated.  Two local vectors with matching indices
are introduced for respectively dummy and actual arguments, and the
loops are modified to use indices and update those argument vectors.

gcc/fortran/
	* gfortran.h (gfc_actual_arglist): New field associated_dummy.
	(gfc_intrinsic_arg): Remove field actual.
	* interface.c (gfc_compare_actual): Initialize associated_dummy.
	* intrinsic.c (sort_actual):  Add argument vectors.
	Use loops with indices on argument vectors.
	Initialize associated_dummy.
---
 gcc/fortran/gfortran.h  |  6 +++++-
 gcc/fortran/interface.c |  9 +++++++--
 gcc/fortran/intrinsic.c | 31 ++++++++++++++++++++-----------
 3 files changed, 32 insertions(+), 14 deletions(-)