[Ada] State refinement predicates for GNATprove

[Arnaud Charlet <charlet at adacore dot com>]

This patch implements two predicates that allow for state revinement queries
while ignoring the region over which a state refinement is visible. No test
possible as this requires an external client of the compiler.

Tested on x86_64-pc-linux-gnu, committed on trunk

2015-11-18  Hristian Kirtchev  <kirtchev@adacore.com>

	* einfo.adb (Has_Non_Null_Refinement): Rename to
	Has_Non_Null_Visible_Refinement.
	(Has_Null_Refinement): Rename to Has_Null_Visible_Refinement.
	* einfo.ads Update the documentation of
	attribute Has_Non_Null_Refinement and attribute Has_Null_Refinement.
	(Has_Non_Null_Refinement): Rename to Has_Non_Null_Visible_Refinement
	and update occurrences in entities.
	(Has_Null_Refinement): Rename to Has_Null_Visible_Refinement and update
	occurrences in entities.
	* sem_prag.adb (Check_In_Out_States): Update the calls to
	Has_[Non_]Null_Refinement.
	(Check_Input_States): Update the
	calls to Has_[Non_]Null_Refinement.
	(Check_Output_States): Update the calls to Has_[Non_]Null_Refinement.
	(Check_Proof_In_States): Update the calls to Has_[Non_]Null_Refinement.
	(Collect_Global_Item): Update the calls to Has_[Non_]Null_Refinement.
	(Is_Null_Refined_State): Update the calls to Has_[Non_]Null_Refinement.
	(Match_Item): Update the calls to Has_[Non_]Null_Refinement.
	* sem_util.adb (Has_Non_Null_Refinement): New routine.
	(Has_Null_Refinement): New routine.
	* sem_util.ads (Has_Non_Null_Refinement): New routine.
	(Has_Null_Refinement): New routine.

Attachment: difs
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