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/scheduler_test.cc b/compiler/optimizing/scheduler_test.cc
index 104ebc7..fb15fc8 100644
--- a/compiler/optimizing/scheduler_test.cc
+++ b/compiler/optimizing/scheduler_test.cc
@@ -182,7 +182,9 @@
     scheduler->Schedule(graph_);
   }
 
-  void CompileWithRandomSchedulerAndRun(const uint16_t* data, bool has_result, int expected) {
+  void CompileWithRandomSchedulerAndRun(const std::vector<uint16_t>& data,
+                                        bool has_result,
+                                        int expected) {
     for (CodegenTargetConfig target_config : GetTargetConfigs()) {
       HGraph* graph = CreateCFG(data);
 
@@ -393,7 +395,7 @@
   //  }
   //  return result;
   //
-  const uint16_t data[] = SIX_REGISTERS_CODE_ITEM(
+  const std::vector<uint16_t> data = SIX_REGISTERS_CODE_ITEM(
     Instruction::CONST_4 | 0 << 12 | 2 << 8,          // const/4 v2, #int 0
     Instruction::CONST_HIGH16 | 0 << 8, 0x4120,       // const/high16 v0, #float 10.0 // #41200000
     Instruction::CONST_4 | 1 << 12 | 1 << 8,          // const/4 v1, #int 1