Support lambda templates.

Support lambda templates.

	* parser.c (cp_parser_lambda_declarator_opt): Accept template parameter
	list with std=c++1y or std=gnu++1y.
	(cp_parser_lambda_body): Don't call 'expand_or_defer_fn' for lambda call
	operator template to avoid adding template result to symbol table.
	* lambda.c (lambda_function): Return template result if call operator is
	a template.
	(maybe_add_lambda_conv_op): Move declarations to point of use.  Refactor
	operator call building in order to support conversion of a non-capturing
	lambda template to a function pointer with help from ...
	(prepare_op_call): ... this new function.
	* decl2.c (check_member_template): Don't reject lambda call operator
	template in local [lambda] class.
	* pt.c (instantiate_class_template_1): Don't instantiate lambda call
	operator template when instantiating lambda class.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@202539 138bc75d-0d04-0410-961f-82ee72b054a4