Make ART compile with GCC -O0 again.

Tidy up InstructionSetFeatures so that it has a type hierarchy dependent on
architecture.
Add to instruction_set_test to warn when InstructionSetFeatures don't agree
with ones from system properties, AT_HWCAP and /proc/cpuinfo.
Clean-up class linker entry point logic to not return entry points but to
test whether the passed code is the particular entrypoint. This works around
image trampolines that replicate entrypoints.
Bug: 17993736

Change-Id: I5f4b49e88c3b02a79f9bee04f83395146ed7be23
diff --git a/runtime/entrypoints/interpreter/interpreter_entrypoints.h b/runtime/entrypoints/interpreter/interpreter_entrypoints.h
index d8b2204..5d646e9 100644
--- a/runtime/entrypoints/interpreter/interpreter_entrypoints.h
+++ b/runtime/entrypoints/interpreter/interpreter_entrypoints.h
@@ -33,10 +33,10 @@
 
 // Pointers to functions that are called by interpreter trampolines via thread-local storage.
 struct PACKED(4) InterpreterEntryPoints {
-  void (*pInterpreterToInterpreterBridge)(Thread* self, MethodHelper& mh,
+  void (*pInterpreterToInterpreterBridge)(Thread* self, MethodHelper* mh,
                                           const DexFile::CodeItem* code_item,
                                           ShadowFrame* shadow_frame, JValue* result);
-  void (*pInterpreterToCompiledCodeBridge)(Thread* self, MethodHelper& mh,
+  void (*pInterpreterToCompiledCodeBridge)(Thread* self, MethodHelper* mh,
                                            const DexFile::CodeItem* code_item,
                                            ShadowFrame* shadow_frame, JValue* result);
 };