third_party: Add the libsync library from Android

third_party/libsync/include/linux/sw_sync.h

Index: third_party/libsync/include/linux/sw_sync.h
diff --git a/third_party/libsync/include/linux/sw_sync.h b/third_party/libsync/include/linux/sw_sync.h
new file mode 100644
index 0000000000000000000000000000000000000000..a8548b22c35e1ab17b3540e98eab15e0eb52ddb9
--- /dev/null
+++ b/third_party/libsync/include/linux/sw_sync.h
@@ -0,0 +1,34 @@
+/*
+ *  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 */