network: Let modules process all ancillary data at once, and adjust UNIX.

This way, modules can decide to do different things based on having
all the ancillary data available. In particular, the UNIX module will
now post only one message header for all the FDs, even if they came
from multiple sets of ancillary data.

This should fix "Message needs unreceived descriptors" from the Chromium
IPC code (which is used by Firefox).

headers/private/net/net_protocol.h

@@ -101,7 +101,7 @@ struct net_protocol_module_info {
 	status_t	(*add_ancillary_data)(net_protocol* self,
 					ancillary_data_container* container, const cmsghdr* header);
 	ssize_t		(*process_ancillary_data)(net_protocol* self,
-					const ancillary_data_header* header, const void* data,
+					const ancillary_data_container* container,
 					void* buffer, size_t bufferSize);
 	ssize_t		(*process_ancillary_data_no_container)(net_protocol* self,
 					net_buffer* buffer, void* data, size_t bufferSize);

headers/private/net/net_stack.h

@@ -180,7 +180,7 @@ struct net_stack_module_info {
 					void* data, bool destroy);
 	void*		(*move_ancillary_data)(ancillary_data_container* from,
 					ancillary_data_container* to);
-	void*		(*next_ancillary_data)(ancillary_data_container* container,
+	void*		(*next_ancillary_data)(const ancillary_data_container* container,
 					void* previousData, ancillary_data_header* _header);
 };