[Ada] gnatbind: Deterministic No_Entry_Calls_In_Elaboration_Code messages

[Ada] gnatbind: Deterministic No_Entry_Calls_In_Elaboration_Code messages

2020-06-08  Bob Duff  <duff@adacore.com>

gcc/ada/

	* bindo-graphs.adb (function Add_Edge): Rename
	Add_Edge_With_Return to Add_Edge; we can tell it returns because
	it's a function, and overloading seems appropriate in this case.
	If Activates_Task=True, and we're not going to add a new edge
	because an existing Pred-->Succ edge already exists, then set
	Activates_Task to True on the preexisting edge.  This ensures
	that the message:

	info: use pragma Restrictions (No_Entry_Calls_In_Elaboration_Code)

	appears when appropriate, no matter in what order the edges
	happened to be processed.
	(procedure Add_Edge): Remove redundant assertions.
	(Activates_Task): Other kinds of edges can have
	Activates_Task=True.  For example, if we had a With_Edge and
	then an Invocation_Edge with Activates_Task=True, then the
	With_Edge has Activates_Task set to True.
	(Add_Edge_Kind_Check): New procedure to prevent other bugs of
	this nature. For example, if we were to sometimes call Add_Edge
	for a Spec_Before_Body_Edge followed by Add_Edge for a
	With_Edge, and sometimes in the other order, that would cause a
	similar bug to what we're fixing here.
	(Set_Is_Recorded_Edge): Val parameter is not used. Get rid of
	it.
	(Set_Activates_Task): New procedure to set the Activates_Task flag.
	* bindo-graphs.ads (Library_Graph_Edge_Kind): Reorder the
	enumeration literals to facilitate Add_Edge_Kind_Check.
	* ali.adb (Known_ALI_Lines): The comment about "still available"
	was wrong. Fix that by erasing the comment, and encoding the
	relevant information in real code. Take advantage of Ada's full
	coverage rules by removing "others =>".  Also DRY.