trans.h (struct gfc_ss_info): Move can_be_null_ref component from the data::scalar subcomponent to the toplevel.

fortran/
	* trans.h (struct gfc_ss_info): Move can_be_null_ref component from
	the data::scalar subcomponent to the toplevel.
	* trans-expr.c (gfc_conv_expr): Update component reference.
	* trans-array.c (gfc_add_loop_ss_code): Ditto.
	(gfc_walk_elemental_function_args): Ditto.  Move the conditional setting
	the field out of the scalar-only block.

From-SVN: r184893