[Ada] Ensure No_Specification_Of_Aspect forbids pragmas and repr. clauses

[Ada] Ensure No_Specification_Of_Aspect forbids pragmas and repr. clauses

gcc/ada/

	* sem_ch13.adb (Analyze_Attribute_Definition_Clause): Add call
	to Check_Restriction_No_Specification_Of_Aspect.
	* sem_prag.adb (Analyze_Pragma): Likewise.
	* restrict.ads (Check_Restriction_No_Specification_Of_Aspect):
	Mention possible new node kinds in documentation.
	* restrict.adb (Check_Restriction_No_Specification_Of_Aspect):
	Retrieve aspect id from different fields if given node is an
	N_Pragma or an N_Attribute_Definition_Clause.