external: new subdirectory for all external libraries and submodules.

You will want to 'make distclean' after this.

I also removed libsecp; we use the one in in libwally anyway.

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

bitcoin/base58.c

@@ -5,7 +5,6 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #include "address.h"
 #include "base58.h"
-#include "libbase58/libbase58.h"
 #include "privkey.h"
 #include "pubkey.h"
 #include "shadouble.h"
@@ -13,6 +12,7 @@
 #include <ccan/build_assert/build_assert.h>
 #include <ccan/tal/str/str.h>
 #include <common/utils.h>
+#include <libbase58.h>
 #include <secp256k1.h>
 #include <string.h>