Replace std::auto_ptr with std::unique_ptr. NFC.

std::auto_ptr has been deprecated in C++11, which some compilers warn
about.

llvm-svn: 261787

polly/include/polly/DependenceInfo.h

@@ -207,7 +207,7 @@ private:
   Scop *S;
 
   /// @brief Dependences struct for the current SCoP.
-  std::auto_ptr<Dependences> D;
+  std::unique_ptr<Dependences> D;
 };
 
 } // End polly namespace.