Describes predefine macros for mbed online compiler (armcc)

Revision:
6:40e873bbc5f7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed/platform/semihost_api.h	Thu Mar 16 21:58:09 2017 +0900
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2015-2016, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MBED_OLD_SEMIHOST_API_H
+#define MBED_OLD_SEMIHOST_API_H
+
+#warning semihost_api.h has been replaced by mbed_semihost_api.h, please update to mbed_semihost_api.h [since mbed-os-5.3]
+#include "platform/mbed_semihost_api.h"
+
+#endif