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/compiler/optimizing/gvn.h b/compiler/optimizing/gvn.h
index 41b3ceb..a98d714 100644
--- a/compiler/optimizing/gvn.h
+++ b/compiler/optimizing/gvn.h
@@ -17,7 +17,6 @@
 #ifndef ART_COMPILER_OPTIMIZING_GVN_H_
 #define ART_COMPILER_OPTIMIZING_GVN_H_
 
-#include <gtest/gtest.h>
 #include "nodes.h"
 
 namespace art {
@@ -221,7 +220,7 @@
   // Mark visisted blocks. Only used for debugging.
   GrowableArray<bool> visited_;
 
-  FRIEND_TEST(GVNTest, LoopSideEffects);
+  ART_FRIEND_TEST(GVNTest, LoopSideEffects);
   DISALLOW_COPY_AND_ASSIGN(GlobalValueNumberer);
 };