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

external/include/sodium/core.h

@@ -0,0 +1,28 @@
+
+#ifndef sodium_core_H
+#define sodium_core_H
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+SODIUM_EXPORT
+int sodium_init(void)
+            __attribute__ ((warn_unused_result));
+
+/* ---- */
+
+SODIUM_EXPORT
+int sodium_set_misuse_handler(void (*handler)(void));
+
+SODIUM_EXPORT
+void sodium_misuse(void)
+            __attribute__ ((noreturn));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif