[Ada] Assertion failure on Default_Initial_Condition

[Ada] Assertion failure on Default_Initial_Condition

This patch prevents the association of a Default_Initial_Condition with
an incomplete type whose full view is the private type or private
extension subject to the aspect/pragma.

2019-07-04  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* sem_util.adb (Propagate_DIC_Attributes): Do not propagate the
	Default_Initial_Condition attributes to an incomplete type.

gcc/testsuite/

	* gnat.dg/default_initial_condition.adb,
	gnat.dg/default_initial_condition_pack.adb,
	gnat.dg/default_initial_condition_pack.ads: New testcase.

From-SVN: r273059