Dexlayout cleanup and refactoring.

Created option to output to a mem map in preparation of hooking
dexlayout into dex2oat.

Test: mm test-art-host-gtest-dexlayout_test
Bug: 29921113
Change-Id: Id42ef15cb8f83cc8d05b025b7647a4338e9b96b0
diff --git a/dexlayout/dex_ir_builder.cc b/dexlayout/dex_ir_builder.cc
index 68ff2a2..d0c5bf9 100644
--- a/dexlayout/dex_ir_builder.cc
+++ b/dexlayout/dex_ir_builder.cc
@@ -71,7 +71,7 @@
     collections.CreateClassDef(dex_file, i);
   }
   // MapItem.
-  collections.SetMapItemOffset(disk_header.map_off_);
+  collections.SetMapListOffset(disk_header.map_off_);
 
   CheckAndSetRemainingOffsets(dex_file, &collections);