add linux tee syscall

src/linux/tee.c

@@ -0,0 +1,8 @@
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include "syscall.h"
+
+ssize_t tee(int src, int dest, size_t len, unsigned flags)
+{
+	return syscall(SYS_tee, src, dest, len, flags);
+}