Move contents of builtins/* to stdlib/*. This simplifies finding stubs.

stdlib/2.7/spwd.pyi

@@ -0,0 +1,15 @@
+from typing import List
+
+class struct_spwd(object):
+    sp_nam = ...  # type: str
+    sp_pwd = ...  # type: str
+    sp_lstchg = ...  # type: int
+    sp_min = ...  # type: int
+    sp_max = ...  # type: int
+    sp_warn = ...  # type: int
+    sp_inact = ...  # type: int
+    sp_expire = ...  # type: int
+    sp_flag = ...  # type: int
+
+def getspall() -> List[struct_spwd]: pass
+def getspnam() -> struct_spwd: pass