[Ada] Fix for visibility of aspect expressions inside generic units

When a generic unit contains references to global entities (i.e.
entities declared outside of this generic unit), those references are
saved: from the analyzed copy of a generic unit (which is then
discarded) into a generic template (which is then instantiated, possibly
many times). To save those references we maintain an association from
nodes in the generic template to nodes in the analyzed copy. However,
this association breaks when analysis of the generic copy calls
Relocate_Node, which conceptually only moves the node, while in fact it
creates a copy with a new Node_Id.

In particular, this association was broken by calls to Relocate_Node
that happen when transforming various aspects into corresponding pragmas
or attribute definition clases. For the most common Pre and Post aspects
this was fixed years ago by not using Relocate_Node and simply sharing
the tree.  This patch extends this fix to other aspects, in particular
those that allow non-static expressions.

gcc/ada/

	* sem_ch13.adb (Relocate_Expression): New routine with code that
	previously was only applied to Pre and Post aspects.
	(Analyze_Aspect_Specifications): Apply the above routine to
	other aspects, in particular to aspects Address, Attach_Handler,
	Predicate and Interrupt_Priority.