amalgamation: include ccan_config.h explicitly

With this change, users of the amalgamation only need to provide
wally-specific defines in their config.h.

Author: jgriffiths

src/amalgamation/combined.c

@@ -33,7 +33,8 @@
 #include "src/secp256k1/src/secp256k1.c"
 #include "src/secp256k1/src/precomputed_ecmult_gen.c"
 #include "src/secp256k1/src/precomputed_ecmult.c"
-#include "src/ccan/ccan/crypto/sha256/sha256.c"
+
+#include "src/ccan_config.h"
 
 #include "src/internal.c"
 #include "src/address.c"
@@ -66,6 +67,9 @@
 #include "src/wif.c"
 #include "src/wordlist.c"
 
+/* ccan sources */
+#include "src/ccan/ccan/crypto/sha256/sha256.c"
+
 /* Redefine internal names so sha-512 can be included without conflicts */
 #define Round Round_512
 #define Transform Transform_512