ada: Small cleanup in finalization machinery

ada: Small cleanup in finalization machinery

This removes an obsolete flag and adjusts a couple of obsolete comments.

gcc/ada/

	* gen_il-fields.ads (Opt_Field_Enum): Remove Is_Finalization_Wrapper
	* gen_il-gen-gen_nodes.adb (N_Block_Statement): Likewise.
	* sinfo.ads (Is_Finalization_Wrapper): Delete.
	* exp_ch7.adb (Build_Finalizer.Process_Declarations): Adjust comment
	and remove obsolete code testing the Is_Finalization_Wrapper flag.
	* exp_util.adb (Requires_Cleanup_Actions): Likewise.