Add missing definition of compile() for 2.7.

stdlib/2.7/__builtin__.pyi

@@ -644,6 +644,8 @@ def any(i: Iterable) -> bool: ...
 def bin(number: int) -> str: ...
 def callable(o: object) -> bool: ...
 def chr(code: int) -> str: ...
+def compile(source: Any, filename: unicode, mode: str, flags: int = 0,
+            dont_inherit: int = 0) -> Any: ...
 def delattr(o: Any, name: unicode) -> None: ...
 def dir(o: object = ...) -> List[str]: ...
 @overload