Update project structure and build process

libwallet/musig/hsort.h

@@ -0,0 +1,22 @@
+/***********************************************************************
+ * Copyright (c) 2021 Russell O'Connor, Jonas Nick                     *
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_HSORT_H_
+#define SECP256K1_HSORT_H_
+
+#include <stddef.h>
+#include <string.h>
+
+/* In-place, iterative heapsort with an interface matching glibc's qsort_r. This
+ * is preferred over standard library implementations because they generally
+ * make no guarantee about being fast for malicious inputs.
+ *
+ * See the qsort_r manpage for a description of the interface.
+ */
+static void secp256k1_hsort(void *ptr, size_t count, size_t size,
+                            int (*cmp)(const void *, const void *, void *),
+                            void *cmp_data);
+#endif