build: clean up forward decls

Author: jgriffiths

include/wally_psbt.h

@@ -61,8 +61,6 @@ extern "C" {
 
 #define WALLY_SCALAR_OFFSET_LEN 32 /* Length of a PSET scalar offset */
 
-struct ext_key;
-
 #ifdef SWIG
 struct wally_psbt_input;
 struct wally_psbt_output;

include/wally_transaction.h

@@ -81,6 +81,8 @@ extern "C" {
 
 struct wally_map;
 #ifdef SWIG
+struct wally_tx_witness_item;
+struct wally_tx_witness_stack;
 struct wally_tx_input;
 struct wally_tx_output;
 struct wally_tx;