[clang][dataflow] Fix -Wrange-loop-construct in DataflowAnalysisConte…

…xt.cpp (NFC)

/llvm-project/clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp:247:10: note: use reference type 'const llvm::Sma
llVector<Atom> &' to prevent copying
    for (const llvm::SmallVector<Atom> Class : Info.EquivalentAtoms)
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                       &
1 error generated.

clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp

@@ -244,7 +244,7 @@ void DataflowAnalysisContext::dumpFlowCondition(Atom Token,
   }
   if (!Info.EquivalentAtoms.empty()) {
     OS << "Equivalent atoms:\n";
-    for (const llvm::SmallVector<Atom> Class : Info.EquivalentAtoms)
+    for (const llvm::SmallVector<Atom> &Class : Info.EquivalentAtoms)
       printAtomList(Class, OS);
   }