Fix a bug which was causing the memory area stuff to fail.

I should probably try to be less clever and use memory area's lower
bounds as the key, and do the extra work required to get that working.


[SVN r42587]

libs/unordered

@@ -1 +1 @@
-Subproject commit 86e01c9c4cc5babbfa08668c2a265c96b3d93e91
+Subproject commit 7d128006e11f582e9b344400c849785e4d2a9e4f