Subzero. X86. Refactors Address Mode formation.

Refactors the Address Mode optimization interface.

BUG=
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1605103002 .
diff --git a/src/IceTargetLoweringARM32.cpp b/src/IceTargetLoweringARM32.cpp
index 0626902..68e8c68 100644
--- a/src/IceTargetLoweringARM32.cpp
+++ b/src/IceTargetLoweringARM32.cpp
@@ -274,7 +274,7 @@
 } // end of anonymous namespace
 
 TargetARM32::TargetARM32(Cfg *Func)
-    : TargetLowering(Func), NeedSandboxing(Ctx->getFlags().getUseSandboxing()),
+    : TargetLowering(Func), NeedSandboxing(SandboxingType == ST_NaCl),
       CPUFeatures(Func->getContext()->getFlags()) {}
 
 void TargetARM32::staticInit(GlobalContext *Ctx) {