Python: Make the All proxy traverse SimObject children as well

This patch changes the behaviour of the All proxy parameter to not
only consider the direct children, but also do a pre-order depth-first
traversal of the object tree and append all results from the
children.

This is used in a later patch to find all the memories in the system,
independent of where they are located in the hierarchy.

src/python/m5/SimObject.py

@@ -865,6 +865,10 @@ class SimObject(object):
             if isinstance(child, ptype) and not isproxy(child) and \
                not isNullPointer(child):
                 all[child] = True
+            if isSimObject(child):
+                # also add results from the child itself
+                child_all, done = child.find_all(ptype)
+                all.update(dict(zip(child_all, [done] * len(child_all))))
         # search param space
         for pname,pdesc in self._params.iteritems():
             if issubclass(pdesc.ptype, ptype):