Update stub for pwd (#1371)

stdlib/2and3/pwd.pyi

@@ -0,0 +1,13 @@
+from typing import List, NamedTuple
+
+struct_passwd = NamedTuple("struct_passwd", [("pw_name", str),
+                                             ("pw_passwd", str),
+                                             ("pw_uid", int),
+                                             ("pw_gid", int),
+                                             ("pw_gecos", str),
+                                             ("pw_dir", str),
+                                             ("pw_shell", str)])
+
+def getpwall() -> List[struct_passwd]: ...
+def getpwuid(uid: int) -> struct_passwd: ...
+def getpwnam(name: str) -> struct_passwd: ...