Bug 1547730 - Define __hash__ for SandboxDependsFunction and CombinedDependsFunction so we can reference it as a dictionary key in py3 r=#build

Differential Revision: https://phabricator.services.mozilla.com/D28111

--HG--
extra : rebase_source : 7d000f29bc3223e778364e16b4ef0d11c646b8f3
extra : intermediate-source : 5848c6841aa71187fb726172b4bbe2553ba87efc
extra : source : 1b31ed5f96344e5f794b4aee6aa8edda4aa3bf2d

python/mozbuild/mozbuild/configure/__init__.py

@@ -78,6 +78,9 @@ class SandboxDependsFunction(object):
     def __eq__(self, other):
         raise ConfigureError('Cannot compare @depends functions.')
 
+    def __hash__(self):
+        return object.__hash__(self)
+
     def __ne__(self, other):
         raise ConfigureError('Cannot compare @depends functions.')
 
@@ -232,6 +235,9 @@ class CombinedDependsFunction(DependsFunction):
                 self._func is other._func and
                 set(self.dependencies) == set(other.dependencies))
 
+    def __hash__(self):
+        return object.__hash__(self)
+
     def __ne__(self, other):
         return not self == other