[Polly] Fix memory leak.

GitOrigin-RevId: 243511a24e5ac134d88178b036d52f151da260ac
diff --git a/lib/Transform/ScheduleOptimizer.cpp b/lib/Transform/ScheduleOptimizer.cpp
index 3806707..2697b32 100644
--- a/lib/Transform/ScheduleOptimizer.cpp
+++ b/lib/Transform/ScheduleOptimizer.cpp
@@ -1662,6 +1662,8 @@
   isl_printer_free(p);
 
   OS << ScheduleStr << "\n";
+
+  free(ScheduleStr);
 }
 
 void IslScheduleOptimizer::getAnalysisUsage(AnalysisUsage &AU) const {