Make the detection context non-constant [NFC]

llvm-svn: 270410
diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index 9aa969a..5cc3336 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -1500,7 +1500,7 @@
   return false;
 }
 
-const ScopDetection::DetectionContext *
+ScopDetection::DetectionContext *
 ScopDetection::getDetectionContext(const Region *R) const {
   auto DCMIt = DetectionContextMap.find(getBBPairForRegion(R));
   if (DCMIt == DetectionContextMap.end())