Ensure inlined static calls perform clinit checks in Optimizing.

Calls to static methods have implicit class initialization
(clinit) checks of the method's declaring class in
Optimizing.  However, when such a static call is inlined,
the implicit clinit check vanishes, possibly leading to an
incorrect behavior.

To ensure that inlining static methods does not change the
behavior of a program, add explicit class initialization
checks (art::HClinitCheck) as well as load class
instructions (art::HLoadClass) as last input of static
calls (art::HInvokeStaticOrDirect) in Optimizing' control
flow graphs, when the declaring class is reachable and not
known to be already initialized.  Then when considering the
inlining of a static method call, proceed only if the method
has no implicit clinit check requirement.

The added explicit clinit checks are already removed by the
art::PrepareForRegisterAllocation visitor.  This CL also
extends this visitor to turn explicit clinit checks from
static invokes into implicit ones after the inlining step,
by removing the added art::HLoadClass nodes mentioned
hereinbefore.

Change-Id: I9ba452b8bd09ae1fdd9a3797ef556e3e7e19c651
diff --git a/compiler/optimizing/graph_checker.h b/compiler/optimizing/graph_checker.h
index 24fee37..45e8804 100644
--- a/compiler/optimizing/graph_checker.h
+++ b/compiler/optimizing/graph_checker.h
@@ -42,6 +42,9 @@
   // Check `instruction`.
   void VisitInstruction(HInstruction* instruction) OVERRIDE;
 
+  // Perform control-flow graph checks on instruction.
+  void VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) OVERRIDE;
+
   // Was the last visit of the graph valid?
   bool IsValid() const {
     return errors_.empty();