Merge pull request #2211 from astavonin/master

export buf_len from ptr

src/libcore/ptr.rs

@@ -9,6 +9,8 @@ export is_null;
 export is_not_null;
 export memcpy;
 export memmove;
+export buf_len;
+export position;
 
 import libc::c_void;
 
@@ -154,4 +156,4 @@ fn test_buf_len() unsafe {
             }
         }
     }
-}
+}