[Ada] Minor internal cleanup in repinfo unit

[Ada] Minor internal cleanup in repinfo unit

This steamlines a bit the implementation.  No functional changes.

2018-05-28  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* repinfo.adb (List_Array_Info): Start with an explicit blank line and
	end with the linker section, if any.
	(List_Entities): Do not output the linker section for record types,
	array types and variables.
	(Print_Expr): Factor out common processing for unary operators and
	special values.  Adjust and reorder the various cases.
	(List_Object_Info): End with the linker section, if any.
	(List_Record_Info): Likewise.
	(List_Type_Info): Do not start with a blank line.

From-SVN: r260815