thirdparty: allow zope.interface.advice to be lazily imported

The symbol from this module is only used in functions. Let's access
that symbol through its imported module so importing
zope.interface.advice can be lazy.

Differential Revision: https://phab.mercurial-scm.org/D2931

mercurial/thirdparty/zope/interface/declarations.py

@@ -34,7 +34,7 b' from types import MethodType'
 from types import ModuleType
 import weakref
 
-from .advice import addClassAdvisor
+from . import advice as advicemod
 from .interface import InterfaceClass
 from .interface import SpecificationBase
 from .interface import Specification
@@ -451,7 +451,7 b' def _implements(name, interfaces, classI'
         raise TypeError(name+" can be used only once in a class definition.")
 
     locals['__implements_advice_data__'] = interfaces, classImplements
-    addClassAdvisor(_implements_advice, depth=3)
+    advicemod.addClassAdvisor(_implements_advice, depth=3)
 
 def implements(*interfaces):
     """Declare interfaces implemented by instances of a class
@@ -732,7 +732,7 b' def classProvides(*interfaces):'
 
     locals["__provides__"] = _normalizeargs(interfaces)
 
-    addClassAdvisor(_classProvides_advice, depth=2)
+    advicemod.addClassAdvisor(_classProvides_advice, depth=2)
 
 def _classProvides_advice(cls):
     # This entire approach is invalid under Py3K.  Don't even try to fix