Fix copy-paste error in TransformIterator.

Test: Rely on TreeHugger.
Bug: 112146806
Change-Id: I7d61bbc025fbce2a77ee0b3824d005d05c9ccec1
diff --git a/libartbase/base/transform_iterator.h b/libartbase/base/transform_iterator.h
index 9265543..5b0574d 100644
--- a/libartbase/base/transform_iterator.h
+++ b/libartbase/base/transform_iterator.h
@@ -71,7 +71,7 @@
     return *this;
   }
 
-  TransformIterator& operator++(int) {
+  TransformIterator operator++(int) {
     TransformIterator tmp(*this);
     ++*this;
     return tmp;
@@ -86,7 +86,7 @@
     return *this;
   }
 
-  TransformIterator& operator--(int) {
+  TransformIterator operator--(int) {
     TransformIterator tmp(*this);
     --*this;
     return tmp;