Reduce memory allocations in dexlayout's CodeFixups.

Using heaptrack for the services.odex compilation of
aosp_taimen-userdebug:
  - before: calls to allocation functions: 5032880
  - after: calls to allocation functions: 4645378

Test: Rely on TreeHugger
Bug: 70331349
Change-Id: I477d5a84e0bf22994ce3de9fe56525de0b498801
diff --git a/dexlayout/dexlayout.cc b/dexlayout/dexlayout.cc
index d904a52..1016fca 100644
--- a/dexlayout/dexlayout.cc
+++ b/dexlayout/dexlayout.cc
@@ -1656,11 +1656,11 @@
           continue;
         }
         // Add const-strings.
-        for (dex_ir::StringId* id : *fixups->StringIds()) {
+        for (dex_ir::StringId* id : fixups->StringIds()) {
           from_hot_method[id->GetIndex()] = true;
         }
         // Add field classes, names, and types.
-        for (dex_ir::FieldId* id : *fixups->FieldIds()) {
+        for (dex_ir::FieldId* id : fixups->FieldIds()) {
           // TODO: Only visit field ids from static getters and setters.
           from_hot_method[id->Class()->GetStringId()->GetIndex()] = true;
           from_hot_method[id->Name()->GetIndex()] = true;
@@ -1668,7 +1668,7 @@
         }
         // For clinits, add referenced method classes, names, and protos.
         if (is_clinit) {
-          for (dex_ir::MethodId* id : *fixups->MethodIds()) {
+          for (dex_ir::MethodId* id : fixups->MethodIds()) {
             from_hot_method[id->Class()->GetStringId()->GetIndex()] = true;
             from_hot_method[id->Name()->GetIndex()] = true;
             is_shorty[id->Proto()->Shorty()->GetIndex()] = true;