Rather than early-include sys/socket.h, let's allow the includer to
tell cody no networking.

	libcody/
	* cody.hh: Allow user to set CODY_NETWORKING.
	gcc/cp/
	* mapper-resolver.cc: Remove early include of
	sys/socket.h.  Specify no CODY_NETWORKING instead.
	* module.cc: Specify no CODY_NETWORKING.