ada: Leave empty parent in an array component of an anonymous access type

ada: Leave empty parent in an array component of an anonymous access type

An itype created for a record component with an anonymous access type has empty
parent. However, a similar itype created for an array component has its parent
copied from the parent of the array type.

The above discrepancy appears to be not needed for the frontend. Also, it is
confusing for the GNATprove backend, because it looks like the itype entity
of the array component comes from a declaration of the array itself.

gcc/ada/ChangeLog:

	* sem_ch3.adb (Array_Type_Declaration): Don't copy parent for an itype
	created by an array component declaration.