[Ada] Spurious visibility error on dynamic_predicate aspect in generic

[Ada] Spurious visibility error on dynamic_predicate aspect in generic

This patch fixes a spurious error when verifying that the visibility of
the expression of an aspect has not changed between the freeze point of
the entity to which it applies, and the end of the enclosing declarative
part. If the entity is a composite type its components must be made
directly visible for the analysis of the expression. In a generic
context this must be done explicitly at the end of the declarative part.

2019-07-08  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch13.adb (Check_Aspect_At_End_Of_Declarations): For an
	unanalized aspect in a generic context that has not been
	analyzed yet, if the aspect applies to a type, place the type on
	the scope stack to make its components visible, before checking
	conformance with the version of the expression analyzed at the
	freeze point.

gcc/testsuite/

	* gnat.dg/predicate8.adb, gnat.dg/predicate8_pkg.adb,
	gnat.dg/predicate8_pkg.ads: New testcase.

From-SVN: r273197