add external dependencies in a pre-built way to avoid incompatibilities

external/include/sodium/crypto_kdf_blake2b.h

@@ -0,0 +1,44 @@
+#ifndef crypto_kdf_blake2b_H
+#define crypto_kdf_blake2b_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "crypto_kdf_blake2b.h"
+#include "export.h"
+
+#ifdef __cplusplus
+# ifdef __GNUC__
+#  pragma GCC diagnostic ignored "-Wlong-long"
+# endif
+extern "C" {
+#endif
+
+#define crypto_kdf_blake2b_BYTES_MIN 16
+SODIUM_EXPORT
+size_t crypto_kdf_blake2b_bytes_min(void);
+
+#define crypto_kdf_blake2b_BYTES_MAX 64
+SODIUM_EXPORT
+size_t crypto_kdf_blake2b_bytes_max(void);
+
+#define crypto_kdf_blake2b_CONTEXTBYTES 8
+SODIUM_EXPORT
+size_t crypto_kdf_blake2b_contextbytes(void);
+
+#define crypto_kdf_blake2b_KEYBYTES 32
+SODIUM_EXPORT
+size_t crypto_kdf_blake2b_keybytes(void);
+
+SODIUM_EXPORT
+int crypto_kdf_blake2b_derive_from_key(unsigned char *subkey, size_t subkey_len,
+                                       uint64_t subkey_id,
+                                       const char ctx[crypto_kdf_blake2b_CONTEXTBYTES],
+                                       const unsigned char key[crypto_kdf_blake2b_KEYBYTES])
+            __attribute__ ((nonnull));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif