one useless futex example, hopefully correct

lkmc/futex.h

@@ -0,0 +1,13 @@
+#ifndef LKMC_FUTEX_H
+#define LKMC_FUTEX_H
+
+static int
+lkmc_futex(int *uaddr, int futex_op, int val,
+        const struct timespec *timeout, int *uaddr2, int val3)
+{
+    (void)uaddr2;
+    return syscall(SYS_futex, uaddr, futex_op, val,
+                    timeout, uaddr, val3);
+}
+
+#endif