Fix comment for Chmod.

R=r, rsc
CC=golang-dev
https://golang.org/cl/183042

src/pkg/os/file.go

@@ -428,7 +428,7 @@ func Rename(oldname, newname string) Error {
 }
 
 // Chmod changes the mode of the named file to mode.
-// If the file is a symbolic link, it changes the uid and gid of the link's target.
+// If the file is a symbolic link, it changes the mode of the link's target.
 func Chmod(name string, mode int) Error {
 	if e := syscall.Chmod(name, mode); e != 0 {
 		return &PathError{"chmod", name, Errno(e)}