sem_ch4.adb (Process_Implicit_Dereference_Prefix): New subprogram used to record...

sem_ch4.adb (Process_Implicit_Dereference_Prefix): New subprogram used to record an implicit dereference as a read operation on...

	* sem_ch4.adb (Process_Implicit_Dereference_Prefix): New subprogram
	used to record an implicit dereference as a read operation on its
	prefix when operating under -gnatc. Necessary to avoid spurious
	'variable assigned but never read' warnings in that mode.
	(Process_Indexed_Component, Analyze_Selected_Component): When the prefix
	is a non-overloaded implicit dereference, call the above subprogram to
	ensure proper recording of references.

From-SVN: r91892