Add libsodium to build

src/3rdparty/sodium/crypto_core_ed25519.h

@@ -0,0 +1,37 @@
+#ifndef crypto_core_ed25519_H
+#define crypto_core_ed25519_H
+
+#include <stddef.h>
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define crypto_core_ed25519_BYTES 32
+SODIUM_EXPORT
+size_t crypto_core_ed25519_bytes(void);
+
+#define crypto_core_ed25519_UNIFORMBYTES 32
+SODIUM_EXPORT
+size_t crypto_core_ed25519_uniformbytes(void);
+
+SODIUM_EXPORT
+int crypto_core_ed25519_is_valid_point(const unsigned char *p);
+
+SODIUM_EXPORT
+int crypto_core_ed25519_add(unsigned char *r,
+                            const unsigned char *p, const unsigned char *q);
+
+SODIUM_EXPORT
+int crypto_core_ed25519_sub(unsigned char *r,
+                            const unsigned char *p, const unsigned char *q);
+
+SODIUM_EXPORT
+int crypto_core_ed25519_from_uniform(unsigned char *p, const unsigned char *r);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif