ART: Clean up allocator.h

Move the single-use typedefs to their users. Remove now-unused
includes. Fix up transitive includes.

Test: m
Change-Id: I953d774b28f1e4f3191f96943e3a69ce66aa398a
diff --git a/runtime/gc/allocator/rosalloc.h b/runtime/gc/allocator/rosalloc.h
index 562fc75..b85d7df 100644
--- a/runtime/gc/allocator/rosalloc.h
+++ b/runtime/gc/allocator/rosalloc.h
@@ -707,6 +707,9 @@
   // the end of the memory region that's ever managed by this allocator.
   size_t max_capacity_;
 
+  template<class Key, AllocatorTag kTag, class Compare = std::less<Key>>
+  using AllocationTrackingSet = std::set<Key, Compare, TrackingAllocator<Key, kTag>>;
+
   // The run sets that hold the runs whose slots are not all
   // full. non_full_runs_[i] is guarded by size_bracket_locks_[i].
   AllocationTrackingSet<Run*, kAllocatorTagRosAlloc> non_full_runs_[kNumOfSizeBrackets];