Replace __unused in kernel headers with __linux_unused to avoid
conflicts with __unused macro in sys/cdefs.h

Change-Id: Ice664397e0b7c7a90795012f30be5e43a9675525
diff --git a/libc/kernel/common/linux/sysctl.h b/libc/kernel/common/linux/sysctl.h
index 46e5e67..5769259 100644
--- a/libc/kernel/common/linux/sysctl.h
+++ b/libc/kernel/common/linux/sysctl.h
@@ -34,7 +34,7 @@
  size_t __user *oldlenp;
  void __user *newval;
  size_t newlen;
- unsigned long __unused[4];
+ unsigned long __linux_unused[4];
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 };
 enum