Revert "Revert "Add implicit null and stack checks for x86""

Fixes x86_64 cross compile issue.  Removes command line options
and property to set implicit checks - this is hard coded now.

This reverts commit 3d14eb620716e92c21c4d2c2d11a95be53319791.

Change-Id: I5404473b5aaf1a9c68b7181f5952cb174d93a90d
diff --git a/compiler/dex/quick/x86/codegen_x86.h b/compiler/dex/quick/x86/codegen_x86.h
index b0c54e8..e40d45e 100644
--- a/compiler/dex/quick/x86/codegen_x86.h
+++ b/compiler/dex/quick/x86/codegen_x86.h
@@ -85,6 +85,7 @@
   LIR* StoreBaseIndexedDisp(RegStorage r_base, RegStorage r_index, int scale, int displacement,
                             RegStorage r_src, OpSize size) OVERRIDE;
   void MarkGCCard(RegStorage val_reg, RegStorage tgt_addr_reg);
+  void GenImplicitNullCheck(RegStorage reg, int opt_flags);
 
   // Required for target - register utilities.
   RegStorage TargetReg(SpecialTargetRegister reg) OVERRIDE;
@@ -798,9 +799,11 @@
    * @param base_reg The register holding the base address.
    * @param offset The offset from the base.
    * @param check_value The immediate to compare to.
+   * @param target branch target (or nullptr)
+   * @param compare output for getting LIR for comparison (or nullptr)
    */
   LIR* OpCmpMemImmBranch(ConditionCode cond, RegStorage temp_reg, RegStorage base_reg,
-                         int offset, int check_value, LIR* target);
+                         int offset, int check_value, LIR* target, LIR** compare);
 
   /*
    * Can this operation be using core registers without temporaries?