Unordered: Merge to release. Fixes #6522.

Fixes undefined macros, removes some unused code and fix some potential issues
for when `std::allocator_traits` is used.


[SVN r76943]

libs/unordered

@@ -1 +1 @@
-Subproject commit 5622afdafa695d0288e0e4e624c8ec58dbf2d15c
+Subproject commit fa3d93ddbcea12be287987022cc235e673576eca