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/utils/arena_allocator.cc b/compiler/utils/arena_allocator.cc
index 516ac2b..0c93f0a 100644
--- a/compiler/utils/arena_allocator.cc
+++ b/compiler/utils/arena_allocator.cc
@@ -15,6 +15,7 @@
  */
 
 #include <algorithm>
+#include <iomanip>
 #include <numeric>
 
 #include "arena_allocator.h"