Make ClassLinker set Class::super_class_ plus test and build improvements

Create placeholder ClassLinker::java_lang_Object_ for use a
super-class of java_lang_Class_ instances.

	src/class_linker.cc
	src/class_linker.h

Expand ClassLinker FindClass test to verify Class::GetSuperClass

	src/class_linker_test.cc

Move DexFile::Load* methods to ClassLinker so they can reference
java_lang_Object_ and java_lang_Class_

	src/class_linker.cc
	src/class_linker.h
	src/dex_file.cc
	src/dex_file.h

Move corresponding Load tests from class_linker_test to dex_file_test

	src/class_linker_test.cc
	src/dex_file_test.cc

Tracking change to object_test to use ClassLinker::Load* methods

	src/object_test.cc

Move base64 to new src/common_test.h for reuse accross tests. Add
missing example source for MyClass dex.

	src/common_test.h
	src/class_linker_test.cc
	src/dex_file_test.cc
	src/object_test.cc

Change Heap::AllocClass to take DexFile argument

	src/heap.h

Remove Method::dex_file_ in favor of using Method::GetClass::GetDexFile

	src/object.cc
	src/object.h

Made a few more RawDexFile methods const

	src/raw_dex_file.cc
	src/raw_dex_file.h

Add convenience targets for build-art and test-art-host

	Android.mk

Drop use of _LOCAL_ from make variants, which isn't the appropriate
here, where we aren't differentiating between LOCAL_ and PRIVATE_.
Avoid redefinition of variables based on now removed
LIBART_TARGET_ARCH and TEST_TARGET_ARCH to support phony targets in
Android.mk

	build/Android.aexec.host.mk
	build/Android.aexec.mk
	build/Android.common.mk
	build/Android.libart.host.mk
	build/Android.libart.mk
	build/Android.test.host.mk
	build/Android.test.mk

Change-Id: I84ce2b7a2b4e37799d4d782b97c02d5e97ac081c
diff --git a/src/object.h b/src/object.h
index 2b75ff7..3bad627 100644
--- a/src/object.h
+++ b/src/object.h
@@ -311,7 +311,7 @@
   }
 
   // const char* GetReturnTypeDescriptor() const {
-  //   return dex_file_->GetRaw()->dexStringByTypeIdx(proto_id_.return_type_id_);
+  //   return klass_->GetDexFile_->GetRaw()->dexStringByTypeIdx(proto_id_.return_type_id_);
   // }
 
   // Returns true if the method is declared public.
@@ -398,10 +398,6 @@
   // method name, e.g. "<init>" or "eatLunch"
   StringPiece name_;
 
-  // A pointer to the DEX file this class was loaded from or NULL for
-  // proxy objects.
-  DexFile* dex_file_;
-
   // Method prototype descriptor string (return and argument types).
   uint32_t proto_idx_;