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.
From-SVN: r202611