Correctly filter . and .. from the file list.

Author: jruderman

src/libcore/os.rs

@@ -467,7 +467,7 @@ fn list_dir(p: path) -> [str] {
     }
 
     rustrt::rust_list_files(star(p)).filter {|filename|
-        !str::eq(filename, ".") || !str::eq(filename, "..")
+        !str::eq(filename, ".") && !str::eq(filename, "..")
     }
 }