[Ada] Improved checking for invalid index values when accessing array elements

[Ada] Improved checking for invalid index values when accessing array elements

gcc/ada/

	* checks.ads: Define a type Dimension_Set. Add an out-mode
	parameter of this new type to Generate_Index_Checks so that
	callers can know for which dimensions a check was generated. Add
	an in-mode parameter of this new type to
	Apply_Subscript_Validity_Checks so that callers can indicate
	that no check is needed for certain dimensions.
	* checks.adb (Generate_Index_Checks): Implement new
	Checks_Generated parameter.
	(Apply_Subscript_Validity_Checks): Implement new No_Check_Needed
	parameter.
	* exp_ch4.adb (Expand_N_Indexed_Component): Call
	Apply_Subscript_Validity_Checks in more cases than before. This
	includes declaring two new local functions,
	(Is_Renamed_Variable_Name,
	Type_Requires_Subscript_Validity_Checks_For_Reads): To help in
	deciding whether to call Apply_Subscript_Validity_Checks.
	Adjust to parameter profile changes in Generate_Index_Checks and
	Apply_Subscript_Validity_Checks.