decl.c (gnat_to_gnu_entity): Filter out negative size for the array dimensions like in the constrained case.

	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Type>: Filter out
	negative size for the array dimensions like in the constrained case.
	<E_Array_Subtype>: Do not create an artificially non-constant high
	bound if the low bound is non-constant.  Minor tweaks.

	* gcc-interface/trans.c (lvalue_required_p): Add CONSTANT parameter
	and turn ALIASED into a boolean parameter.  Adjust calls to self.
	<N_Attribute_Reference>: Return 1 for more attributes.
	<N_Object_Renaming_Declaration>: Return 1 for non-constant objects.
	<N_Assignment_Statement>: Return 1 for the LHS.
	(Identifier_to_gnu): Adjust calls to lvalue_required_p.
	(call_to_gnu): Be prepared for wrapped boolean rvalues.

From-SVN: r152201