Make out arguments non-reference types.

Also, tidy some portable related code.

Change-Id: I67c8aa52eef8b556ca117ecda1b1e75465ba06a5
diff --git a/compiler/dex/compiler_ir.h b/compiler/dex/compiler_ir.h
index 8447d23..b9a26d6 100644
--- a/compiler/dex/compiler_ir.h
+++ b/compiler/dex/compiler_ir.h
@@ -64,7 +64,7 @@
   const CompilerBackend* compiler_backend;
   InstructionSet instruction_set;
 
-  const InstructionSetFeatures& GetInstructionSetFeatures() {
+  InstructionSetFeatures GetInstructionSetFeatures() {
     return compiler_driver->GetInstructionSetFeatures();
   }
   // TODO: much of this info available elsewhere.  Go to the original source?