libcrypto: Avoid double free

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/libcrypto.c

@@ -437,7 +437,6 @@ HMACCTX hmac_init(const void *key, int len, enum ssh_hmac_e type) {
       break;
     default:
       HMAC_CTX_free(ctx);
-      SAFE_FREE(ctx);
       ctx = NULL;
   }