ssh: only test callbacks for libssh2

There are no custom callbacks for OpenSSH; don't test them.

tests/libgit2/online/clone.c

@@ -653,7 +653,7 @@ void test_online_clone__ssh_auth_methods(void)
 {
 	int with_user;
 
-#ifndef GIT_SSH
+#ifndef GIT_SSH_LIBSSH2
 	clar__skip();
 #endif
 	g_options.fetch_opts.callbacks.credentials = check_ssh_auth_methods;
@@ -796,6 +796,7 @@ void test_online_clone__ssh_cannot_change_username(void)
 #ifndef GIT_SSH_LIBSSH2
 	clar__skip();
 #endif
+
 	g_options.fetch_opts.callbacks.credentials = cred_foo_bar;
 
 	cl_git_fail(git_clone(&g_repo, "ssh://git@github.com/libgit2/TestGitRepository", "./foo", &g_options));
@@ -837,6 +838,10 @@ static int ssh_certificate_check(git_cert *cert, int valid, const char *host, vo
 
 void test_online_clone__ssh_cert(void)
 {
+#ifndef GIT_SSH_LIBSSH2
+	cl_skip();
+#endif
+
 	g_options.fetch_opts.callbacks.certificate_check = ssh_certificate_check;
 
 	if (!_remote_ssh_fingerprint)
@@ -911,7 +916,7 @@ void test_online_clone__certificate_invalid(void)
 	cl_git_fail_with(GIT_ECERTIFICATE,
 		git_clone(&g_repo, "https://github.com/libgit2/TestGitRepository", "./foo", &g_options));
 
-#ifdef GIT_SSH
+#ifdef GIT_SSH_LIBSSH2
 	cl_git_fail_with(GIT_ECERTIFICATE,
 		git_clone(&g_repo, "ssh://github.com/libgit2/TestGitRepository", "./foo", &g_options));
 #endif