[Ada] In a generic use Presanalyze_Spec_Expression on Predicates

[Ada] In a generic use Presanalyze_Spec_Expression on Predicates

When verifying that the meaning of an aspect has not changed between the
freeze point of the entity and the end of the declarations, we analkyze
a copy of the expression to verify its conformance to previous analysis.
If the expression contains overloaded references, these have to be
resolved, which is not done if the expression is only preanalyzed.  This
applies in particular to expressions in predicates.

2019-09-17  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch13.adb (Check_Aspect_At_End_Of_Declarations): In a
	generic context, for a Predicate aspect, use
	Preanalyze_Spec_Expression to verify conformance.

gcc/testsuite/

	* gnat.dg/predicate13.adb, gnat.dg/predicate13.ads: New
	testcase.

From-SVN: r275778