Sycl implementation for objective functions (#9846)

---------

Co-authored-by: Dmitry Razdoburdin <>

tests/cpp/objective/test_multiclass_obj.h

@@ -0,0 +1,19 @@
+/**
+ * Copyright 2020-2023 by XGBoost Contributors
+ */
+#ifndef XGBOOST_TEST_MULTICLASS_OBJ_H_
+#define XGBOOST_TEST_MULTICLASS_OBJ_H_
+
+#include <xgboost/context.h>  // for Context
+
+namespace xgboost {
+
+void TestSoftmaxMultiClassObjGPair(const Context* ctx);
+
+void TestSoftmaxMultiClassBasic(const Context* ctx);
+
+void TestSoftprobMultiClassBasic(const Context* ctx);
+
+}  // namespace xgboost
+
+#endif  // XGBOOST_TEST_MULTICLASS_OBJ_H_