Fortran : ICE in gfc_conv_scalarized_array_ref PR53298

When an array of characters is an argument to a subroutine and
is accessed using (:)(1:) an ICE occurs.  The upper bound of the
substring does not have an expression and such should not have
a Scalarization State structure added to the Scalarization State
chain.

2020-07-29  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/fortran/

	PR fortran/53298
	* trans-array.c (gfc_walk_array_ref): If ref->ss.end is set
	call gfc_get_scalar_ss.

2020-07-29  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/testsuite/

	PR fortran/53298
	* gfortran.dg/pr53298.f90: New test.