ada: Check global mode restriction on encapsulating abstract states

ada: Check global mode restriction on encapsulating abstract states

We already checked that a global item of mode Output is not an Input of
the enclosing subprograms. With this change we also check that if this
global item is a constituent, then none of its encapsulating abstract
states is an Input of the enclosing subprograms.

gcc/ada/

	* sem_prag.adb (Check_Mode_Restriction_In_Enclosing_Context):
	Iterate over encapsulating abstract states.