Fix structural class checks

Enabled for debug builds to prevent bit rotting. Changed
DexFileAndClassPair to work with std::queue.

Re-enabled structural check tests.

Change-Id: Ia981564650bf1c7e418d8a73efcc15733ddf7501
diff --git a/runtime/native/dalvik_system_DexFile.cc b/runtime/native/dalvik_system_DexFile.cc
index e9ce02b..8e6eae9 100644
--- a/runtime/native/dalvik_system_DexFile.cc
+++ b/runtime/native/dalvik_system_DexFile.cc
@@ -74,7 +74,7 @@
                                              const OatFile* oat_file,
                                              std::vector<std::unique_ptr<const DexFile>>& vec) {
   // Add one for the oat file.
-  jlongArray long_array = env->NewLongArray(static_cast<jsize>(1u + vec.size()));
+  jlongArray long_array = env->NewLongArray(static_cast<jsize>(kDexFileIndexStart + vec.size()));
   if (env->ExceptionCheck() == JNI_TRUE) {
     return nullptr;
   }