change empty bodies from "pass" to "..."

CONTRIBUTING.md says to prefer ... Not the most impactful change but fixing
these will allow us to lint for it in the future and get a consistent style.

stdlib/2/__builtin__.pyi

@@ -24,8 +24,8 @@ _T3 = TypeVar('_T3')
 _T4 = TypeVar('_T4')
 _TT = TypeVar('_TT', bound='type')
 
-class staticmethod: pass   # Special, only valid as a decorator.
-class classmethod: pass  # Special, only valid as a decorator.
+class staticmethod: ...   # Special, only valid as a decorator.
+class classmethod: ...  # Special, only valid as a decorator.
 
 class object:
     __doc__ = ...  # type: Optional[str]

stdlib/2/encodings/utf_8.pyi

@@ -9,6 +9,6 @@ class StreamWriter(codecs.StreamWriter):
 class StreamReader(codecs.StreamReader):
     pass
 
-def getregentry() -> codecs.CodecInfo: pass
-def encode(input: str, errors: str = ...) -> bytes: pass
-def decode(input: bytes, errors: str = ...) -> str: pass
+def getregentry() -> codecs.CodecInfo: ...
+def encode(input: str, errors: str = ...) -> bytes: ...
+def decode(input: bytes, errors: str = ...) -> str: ...

stdlib/2/spwd.pyi

@@ -11,5 +11,5 @@ class struct_spwd(object):
     sp_expire = ...  # type: int
     sp_flag = ...  # type: int
 
-def getspall() -> List[struct_spwd]: pass
-def getspnam() -> struct_spwd: pass
+def getspall() -> List[struct_spwd]: ...
+def getspnam() -> struct_spwd: ...

stdlib/2/types.pyi

@@ -127,7 +127,7 @@ class FrameType:
     f_restricted = ...  # type: bool
     f_trace = ...  # type: Callable[[], None]
 
-    def clear(self) -> None: pass
+    def clear(self) -> None: ...
 
 SliceType = slice
 class EllipsisType: ...