c++/48320 - Template parameter packs cannot be expanded in default template arguments

c++/48320 - Template parameter packs cannot be expanded in default template arguments

gcc/cp/

	PR c++/48320
	* pt.c (template_parameter_pack_p):  Support TEMPLATE_PARM_INDEX
	nodes.  Add a comment.
	(arg_from_parm_pack_p):  New static function, factorized out from
	tsubst_pack_expansion and extended to support non-type parameter
	packs represented with TEMPLATE_PARM_INDEX nodes.
	(tsubst_pack_expansion): Use arg_from_parm_pack_p.

gcc/testsuite/

	PR c++/48320
	* g++.dg/cpp0x/variadic116.C: New test case.

From-SVN: r178811