PR libstdc++/71444
	* config/os/mingw32-w64/error_constants.h
	(address_family_not_supported, address_in_use, address_not_available)
	(already_connected, connection_aborted, connection_already_in_progress)
	connection_refused, connection_reset, cross_device_link)
	(destination_address_required, host_unreachable, message_size)
	(network_down, network_reset, network_unreachable, no_buffer_space)
	(no_protocol_option, not_a_socket, not_connected, operation_canceled)
	(operation_in_progress, operation_not_supported, protocol_error)
	(protocol_not_supported, too_many_links, too_many_symbolic_link_levels)
	(value_too_large, wrong_protocol_type): Define.
	(bad_message, identifier_removed, no_link, no_message_available)
	(no_message, no_stream_resources, not_a_stream, owner_dead)
	(state_not_recoverable, stream_timeout, text_file_busy): Define
	conditionally.
	* testsuite/19_diagnostics/headers/system_error/errc_std_c++0x.cc:
	Guard test for no_message with _GLIBCXX_HAVE_ENOMSG.

From-SVN: r243853