Subzero: Fix a mul lowering error.

src/IceTargetLoweringARM32.h

Index: src/IceTargetLoweringARM32.h
diff --git a/src/IceTargetLoweringARM32.h b/src/IceTargetLoweringARM32.h
index c5654be401c6d34817c1377f78798cc4f57d348b..00f1483264d714d80b78d1c15eda0f1ad6a461af 100644
--- a/src/IceTargetLoweringARM32.h
+++ b/src/IceTargetLoweringARM32.h
@@ -763,6 +763,7 @@ protected:
     // Model the modification to the second dest as a fake def. Note that the
     // def is not predicated.
     Context.insert<InstFakeDef>(DestHi, DestLo);
+    Context.insert<InstFakeUse>(DestHi);
   }
   void _uxt(Variable *Dest, Variable *Src0,
             CondARM32::Cond Pred = CondARM32::AL) {