declare soup_ssl_supported.

declare soup_ssl_supported.

	* libsoup/soup-misc.h: declare soup_ssl_supported.

	* libsoup/soup-gnutls.c: add soup_ssl_supported declaration.

	* libsoup/soup-nossl.c: Not an SSL implementation, built if
	HAVE_SSL is not defined.

	* libsoup/Makefile.am (libsoup_2_2_la_SOURCES): add soup-nossl.c

	* libsoup/soup-socket.c (soup_socket_start_ssl): Return success or
	failure.
	(listen_watch): Deal with soup_socket_start_ssl failing.

	* libsoup/soup-connection.c (tunnel_connect_finished,
	socket_connect_result, soup_connection_connect_sync): Deal with
	the soup_socket_start_ssl failing.

	* libsoup/soup-server.c (soup_server_new): Deal with
	soup_ssl_get_server_credentials failing