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

external/include/sodium/randombytes_internal_random.h

@@ -0,0 +1,22 @@
+
+#ifndef randombytes_internal_random_H
+#define randombytes_internal_random_H
+
+#include "export.h"
+#include "randombytes.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+SODIUM_EXPORT
+extern struct randombytes_implementation randombytes_internal_implementation;
+
+/* Backwards compatibility with libsodium < 1.0.18 */
+#define randombytes_salsa20_implementation randombytes_internal_implementation
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif