Add MariaDB Connector/C as a built-in alternative (v3.2.3).

vendor/MDBC/plugins/auth/ref10/keypair.c

@@ -0,0 +1,23 @@
+#include <string.h>
+#include "crypto_sign.h"
+#include "crypto_hash_sha512.h"
+#include "ge.h"
+
+int crypto_sign_keypair(
+  unsigned char *pk,
+  unsigned char *pw, unsigned long long pwlen
+)
+{
+  unsigned char az[64];
+  ge_p3 A;
+
+  crypto_hash_sha512(az,pw,pwlen);
+  az[0] &= 248;
+  az[31] &= 63;
+  az[31] |= 64;
+
+  ge_scalarmult_base(&A,az);
+  ge_p3_tobytes(pk,&A);
+
+  return 0;
+}