third_party: Add the libsync library from Android

third_party/libsync/include/linux/sw_sync.h

+/*
+ *  Copyright 2016 Google, Inc
+ *
+ *  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 _UAPI_LINUX_SW_SYNC_H
+#define _UAPI_LINUX_SW_SYNC_H
+
+#include <linux/types.h>
+
+struct sw_sync_create_fence_data {
+        __u32   value;
+        char    name[32];
+        __s32   fence; /* fd of new fence */
+};
+
+#define SW_SYNC_IOC_MAGIC       'W'
+
+#define SW_SYNC_IOC_CREATE_FENCE        _IOWR(SW_SYNC_IOC_MAGIC, 0,\
+                struct sw_sync_create_fence_data)
+#define SW_SYNC_IOC_INC                 _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
+
+#endif /* _UAPI_LINUX_SW_SYNC_H */