[Ada] Spurious error on aggregate with choice that is predicted subtype

[Ada] Spurious error on aggregate with choice that is predicted subtype

This patch fixes a spurious error on a record aggregate for a variant
record when a choice in the aggregate is given by a subtype with a
static predicate. The same expansion mechanism for such a variant, used
in case statements, must be used here as well.

2019-07-05  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_util.adb (Encloing_Subprogram): If Enclosing_Dynamic_Scope
	is a loop, continue climbing the scope stack to find the
	enclosing subprogram.
	(Gather_Components): Handle properly a choice in a record
	aggregate that is given by a subtype with a static predicate.

gcc/testsuite/

	* gnat.dg/aggr25.adb, gnat.dg/aggr25.ads: New testcase.

From-SVN: r273112