[Ada] Fix iterated component association for array aggregate

[Ada] Fix iterated component association for array aggregate

Create a scope for the Ada 2022 iterated component association loops. In
the case of elements needing finalization, the late expansion would
crash on references to the loop variable within the loop body.

gcc/ada/

	* exp_aggr.adb (Gen_Loop): Create scope for loop variable of
	iterated components.