eng_devcrypto: don't leak methods tables

Call functions to prepare methods after confirming that /dev/crytpo was
sucessfully open and that the destroy function has been set.

Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7585)

(cherry picked from commit d9d4dff5c6)

crypto/engine/eng_devcrypto.c

@@ -619,11 +619,6 @@ void engine_load_devcrypto_int()
         return;
     }
 
-    prepare_cipher_methods();
-#ifdef IMPLEMENT_DIGEST
-    prepare_digest_methods();
-#endif
-
     if ((e = ENGINE_new()) == NULL
         || !ENGINE_set_destroy_function(e, devcrypto_unload)) {
         ENGINE_free(e);
@@ -636,6 +631,11 @@ void engine_load_devcrypto_int()
         return;
     }
 
+    prepare_cipher_methods();
+#ifdef IMPLEMENT_DIGEST
+    prepare_digest_methods();
+#endif
+
     if (!ENGINE_set_id(e, "devcrypto")
         || !ENGINE_set_name(e, "/dev/crypto engine")