Fix allocator::map template argument ordering

allocator::map reversed Key and T from std::map

Bug: 27208635
Change-Id: I4e4db704539d01b060cb948aa573cb674da48c7d
diff --git a/libmemunreachable/HeapWalker.h b/libmemunreachable/HeapWalker.h
index b338933..7b851c4 100644
--- a/libmemunreachable/HeapWalker.h
+++ b/libmemunreachable/HeapWalker.h
@@ -74,7 +74,7 @@
 
   DISALLOW_COPY_AND_ASSIGN(HeapWalker);
   Allocator<HeapWalker> allocator_;
-  using AllocationMap = allocator::map<AllocationInfo, Range, compare_range>;
+  using AllocationMap = allocator::map<Range, AllocationInfo, compare_range>;
   AllocationMap allocations_;
   size_t allocation_bytes_;
   Range valid_allocations_range_;