ART: Fix leak in codegen_test

Make sure the InstructionSetFeatures isn't leaked.

Change-Id: Ide25773500c1513ecb204a380bb0a95513ff7276
diff --git a/compiler/optimizing/codegen_test.cc b/compiler/optimizing/codegen_test.cc
index 4c06e23..18722f7 100644
--- a/compiler/optimizing/codegen_test.cc
+++ b/compiler/optimizing/codegen_test.cc
@@ -88,7 +88,9 @@
     Run(allocator, codegenX86, has_result, expected);
   }
 
-  arm::CodeGeneratorARM codegenARM(graph, ArmInstructionSetFeatures::FromCppDefines());
+  std::unique_ptr<const ArmInstructionSetFeatures> features(
+      ArmInstructionSetFeatures::FromCppDefines());
+  arm::CodeGeneratorARM codegenARM(graph, features.get());
   codegenARM.CompileBaseline(&allocator, true);
   if (kRuntimeISA == kArm || kRuntimeISA == kThumb2) {
     Run(allocator, codegenARM, has_result, expected);