[clang][dataflow] Fix broken build in ClangStaticAnalyzer

Adds a missing virtual destructor.
diff --git a/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
index 2164741..9448b91 100644
--- a/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
+++ b/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
@@ -40,6 +40,8 @@
 /// Type-erased base class for dataflow analyses built on a single lattice type.
 class TypeErasedDataflowAnalysis {
 public:
+  virtual ~TypeErasedDataflowAnalysis() {}
+
   /// Returns the `ASTContext` that is used by the analysis.
   virtual ASTContext &getASTContext() = 0;