[StructurizeCFG] Add whitespace in getAnalysisUsage.

[jlebar]

Summary

"addRequired" and "addPreserved" look very similar when squished up next
to each other -- without the newline this code looked to me like it was
addRequired'ing DominatorTreeWrapperPass twice.

[arsenm]

LGTM

llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp

public:
   StringRef getPassName() const override { return "Structurize control flow"; }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     if (SkipUniformRegions)
       AU.addRequired<DivergenceAnalysis>();
     AU.addRequiredID(LowerSwitchID);
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<LoopInfoWrapperPass>();
+
     AU.addPreserved<DominatorTreeWrapperPass>();
     RegionPass::getAnalysisUsage(AU);
   }
 };
 
 } // end anonymous namespace
 
 char StructurizeCFG::ID = 0;