add linux tee syscall

include/fcntl.h

@@ -130,6 +130,7 @@ ssize_t readahead(int, off_t, size_t);
 int sync_file_range(int, off_t, off_t, unsigned);
 ssize_t vmsplice(int, const struct iovec *, size_t, unsigned);
 ssize_t splice(int, off_t *, int, off_t *, size_t, unsigned);
+ssize_t tee(int, int, size_t, unsigned);
 #define loff_t off_t
 #endif
 

src/linux/tee.c

+#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);
+}