Cannot have the base class destructor be private (or explicitly deleted); fixing the build bots.

llvm-svn: 205916

clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h

@@ -220,10 +220,6 @@ protected:
   unsigned short Flags;
 
 private:
-  // Note, this cannot be explicitly deleted due to initializers automatically
-  // referencing destructor declarations. However, it does not need to be
-  // defined because that reference does not require an definition.
-  ~SExpr();
   SExpr() = delete;
 
   // SExpr objects must be created in an arena and cannot be deleted.