[optimizing] Add basic PackedSwitch support

Add HPackedSwitch, and generate it from the builder.  Code generators
convert this to a series of compare/branch tests.  Better implementation
in the code generators as a real jump table will follow as separate CLs.

Change-Id: If14736fa4d62809b6ae95280148c55682e856911
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>
diff --git a/compiler/optimizing/graph_checker.h b/compiler/optimizing/graph_checker.h
index 0e270db..7ddffc1 100644
--- a/compiler/optimizing/graph_checker.h
+++ b/compiler/optimizing/graph_checker.h
@@ -125,6 +125,7 @@
   void VisitBinaryOperation(HBinaryOperation* op) OVERRIDE;
   void VisitCondition(HCondition* op) OVERRIDE;
   void VisitIf(HIf* instruction) OVERRIDE;
+  void VisitPackedSwitch(HPackedSwitch* instruction) OVERRIDE;
   void VisitBooleanNot(HBooleanNot* instruction) OVERRIDE;
   void VisitConstant(HConstant* instruction) OVERRIDE;