connectd: add annotation and fix up formatting on connectd/netaddress.c

This is stolen from the bitcoind source, so we use their style
(no tabs, 4-wide spaces).  Clean it up and add the emacs magic to
maintain it in future.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

connectd/netaddress.c

@@ -1,3 +1,4 @@
+/* -*- c-basic-offset: 4; indent-tabs-mode: nil; -*- */
 #include <arpa/inet.h>
 #include <assert.h>
 #include <common/status.h>