forward_list.h (forward_list(size_type)): Add missing allocator parameter.

	* include/bits/forward_list.h (forward_list(size_type)): Add missing
	allocator parameter.
	(_Fwd_list_node_base): Use NSDMI and define constructor as defaulted.
	(_Fwd_list_node::_M_value): Replace with uninitialized storage.
	(_Fwd_list_node::_M_valptr()): Define functions to access storage.
	(_Fwd_list_iterator, _Fwd_list_const_iterator): Use _M_valptr.
	(_Fwd_list_base::_M_create_node): Only use allocator to construct the
	element not the node.
	* include/bits/forward_list.tcc (_Fwd_list_base::_M_erase_after): Only
	use allocator to destroy the element not the node.
	* testsuite/23_containers/forward_list/cons/11.cc: Remove unused
	headers.
	* testsuite/23_containers/forward_list/cons/12.cc: Likewise.
	* testsuite/23_containers/forward_list/cons/13.cc: New.
	* testsuite/23_containers/forward_list/cons/14.cc: New.

From-SVN: r193086