[Ada] Spurious error on inst. of partially defaulted formal package

[Ada] Spurious error on inst. of partially defaulted formal package

This patch removes a spurious error on an instantiation whose generic
unit has a formal package where some formal parameters are
box-initialiaed.  Previously the code assumed that box-initialization
for a formal package applied to all its formal parameters.

2019-07-01  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch12.adb (Is_Defaulted): New predicate in
	Check_Formal_Package_Intance, to skip the conformance of checks
	on parameters of a formal package that are defaulted,

gcc/testsuite/

	* gnat.dg/generic_inst3.adb,
	gnat.dg/generic_inst3_kafka_lib-topic.ads,
	gnat.dg/generic_inst3_kafka_lib.ads,
	gnat.dg/generic_inst3_markets.ads,
	gnat.dg/generic_inst3_traits-encodables.ads,
	gnat.dg/generic_inst3_traits.ads: New testcase.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@272883 138bc75d-0d04-0410-961f-82ee72b054a4