* einfo.ads (Size_Depends_On_Discriminant): Adjust description.
	* layout.adb (Compute_Size_Depends_On_Discriminant): New procedure
	to compute Set_Size_Depends_On_Discriminant.
	(Layout_Type): Call it on array types in back-end layout mode.
	* sem_util.adb (Requires_Transient_Scope): Return true for array
	types only if the size depends on the value of discriminants.
	* gcc-interface/utils2.c (build_binary_op) <MODIFY_EXPR>: Use the RHS
	type if the RHS is a call to a function that returns an unconstrained
	type with default discriminant.

From-SVN: r171402