Clean up NullCheck generation and record stats about it.

This removes redundant code from the generators and allows for easier
stat recording.

Change-Id: Iccd4368f9e9d87a6fecb863dee4e2145c97851c4
diff --git a/compiler/optimizing/code_generator_mips.h b/compiler/optimizing/code_generator_mips.h
index 605c794..b720573 100644
--- a/compiler/optimizing/code_generator_mips.h
+++ b/compiler/optimizing/code_generator_mips.h
@@ -226,8 +226,6 @@
   void HandleShift(HBinaryOperation* operation);
   void HandleFieldSet(HInstruction* instruction, const FieldInfo& field_info, uint32_t dex_pc);
   void HandleFieldGet(HInstruction* instruction, const FieldInfo& field_info, uint32_t dex_pc);
-  void GenerateImplicitNullCheck(HNullCheck* instruction);
-  void GenerateExplicitNullCheck(HNullCheck* instruction);
   void GenerateIntCompare(IfCondition cond, LocationSummary* locations);
   void GenerateIntCompareAndBranch(IfCondition cond,
                                    LocationSummary* locations,
@@ -362,6 +360,8 @@
   }
 
   void GenerateNop();
+  void GenerateImplicitNullCheck(HNullCheck* instruction);
+  void GenerateExplicitNullCheck(HNullCheck* instruction);
 
  private:
   // Labels for each block that will be compiled.