[NFC] Use releaseMemory to release internal memory

llvm-svn: 248684
diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 3193e26..e573a6d 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -335,12 +335,10 @@
 private:
   isl_schedule *LastSchedule;
 
-  using llvm::Pass::doFinalization;
-
-  virtual bool doFinalization() override {
+  /// @brief Release the internal memory.
+  void releaseMemory() override {
     isl_schedule_free(LastSchedule);
     LastSchedule = nullptr;
-    return true;
   }
 };
 }