Change compiler tests to have aligned code item

Previously, the code item was not necessarily 32 bit aligned. This
caused bus errors on armv7.

Also create a real dexfile object instead of casting 0 initialized
memory to a dex file pointer. We just got lucky before that the cdex
boolean was false.

Test: test-art-target-gtest
Bug: 63756964
Bug: 71605148

Change-Id: Ic7199f2b97bbd421de1d702efa5c6531ff45c022
diff --git a/compiler/optimizing/optimizing_cfi_test.cc b/compiler/optimizing/optimizing_cfi_test.cc
index e2b2106..d20b681 100644
--- a/compiler/optimizing/optimizing_cfi_test.cc
+++ b/compiler/optimizing/optimizing_cfi_test.cc
@@ -41,7 +41,7 @@
 // Run the tests only on host.
 #ifndef ART_TARGET_ANDROID
 
-class OptimizingCFITest : public CFITest {
+class OptimizingCFITest : public CFITest, public OptimizingUnitTestHelper {
  public:
   // Enable this flag to generate the expected outputs.
   static constexpr bool kGenerateExpected = false;
@@ -63,7 +63,7 @@
     // Setup simple context.
     std::string error;
     isa_features_ = InstructionSetFeatures::FromVariant(isa, "default", &error);
-    graph_ = CreateGraph(&pool_and_allocator_);
+    graph_ = CreateGraph();
     // Generate simple frame with some spills.
     code_gen_ = CodeGenerator::Create(graph_, isa, *isa_features_, opts_);
     code_gen_->GetAssembler()->cfi().SetEnabled(true);