Change Stat to Lstat in Readdir so we don't recur when someone symlinks "."

R=rsc
CC=go-dev
http://go/go-review/1018003

src/pkg/os/file.go

@@ -315,7 +315,7 @@ func (file *File) Readdir(count int) (dirs []Dir, err Error) {
 	}
 	dirs = make([]Dir, len(names));
 	for i, filename := range names {
-		dirp, err := Stat(dirname+filename);
+		dirp, err := Lstat(dirname+filename);
 		if dirp == nil || err != nil {
 			dirs[i].Name = filename;	// rest is already zeroed out
 		} else {