homed: move helper calls for RSA encryption to shared code

src/shared/openssl-util.h

@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
+#include "macro.h"
+
 #if HAVE_OPENSSL
 #  include <openssl/pem.h>
 
@@ -9,4 +11,6 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(X509_NAME*, X509_NAME_free);
 DEFINE_TRIVIAL_CLEANUP_FUNC(EVP_PKEY_CTX*, EVP_PKEY_CTX_free);
 DEFINE_TRIVIAL_CLEANUP_FUNC(EVP_CIPHER_CTX*, EVP_CIPHER_CTX_free);
 
+int rsa_encrypt_bytes(EVP_PKEY *pkey, const void *decrypted_key, size_t decrypted_key_size, void **ret_encrypt_key, size_t *ret_encrypt_key_size);
+
 #endif