Update ccan/structeq.

structeq() is too dangerous: if a structure has padding, it can fail
silently.

The new ccan/structeq instead provides a macro to define foo_eq(),
which does the right thing in case of padding (which none of our
structures currently have anyway).

Upgrade ccan, and use it everywhere.  Except run-peer-wire.c, which
is only testing code and can use raw memcmp(): valgrind will tell us
if padding exists.

Interestingly, we still declared short_channel_id_eq, even though
we didn't define it any more!

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

bitcoin/privkey.h

@@ -2,11 +2,14 @@
 #define LIGHTNING_BITCOIN_PRIVKEY_H
 #include "config.h"
 #include <ccan/short_types/short_types.h>
+#include <ccan/structeq/structeq.h>
 
 /* General 256-bit secret, which must be private.  Used in various places. */
 struct secret {
 	u8 data[32];
 };
+/* Define secret_eq */
+STRUCTEQ_DEF(secret, 0, data);
 
 /* This is a private key.  Keep it secret. */
 struct privkey {