re PR fortran/19928 (Reference of constant derived type component causes failure)

re PR fortran/19928 (Reference of constant derived type component causes failure)

	PR fortran/19928
	* trans-array.c (gfc_conv_array_ref): Call gfc_advance_se_ss_chain
	after handling scalarized references.  Make "indexse" inherit from
	"se" when handling AR_ELEMENTs.
	(gfc_walk_variable_expr): Add GFC_SS_SCALAR entries for each
	substring or scalar reference that follows an array section.
	* trans-expr.c (gfc_conv_variable): When called from within a
	scalarization loop, start out with "ref" pointing to the scalarized
	part of the reference.  Don't call gfc_advance_se_ss_chain here.

From-SVN: r104035