syscall: sendfile

R=iant
CC=golang-dev
https://golang.org/cl/4553051

src/pkg/syscall/syscall_linux_amd64.go

@@ -22,6 +22,7 @@ package syscall
 //sys	Pwrite(fd int, p []byte, offset int64) (n int, errno int) = SYS_PWRITE64
 //sys	Seek(fd int, offset int64, whence int) (off int64, errno int) = SYS_LSEEK
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, errno int)
+//sys	Sendfile(outfd int, infd int, offset *int64, count int) (written int, errno int)
 //sys	Setfsgid(gid int) (errno int)
 //sys	Setfsuid(uid int) (errno int)
 //sysnb	Setgid(gid int) (errno int)