Change a C-style cast to const_cast, to avoid a -Wcast-qual warning.

llvm-svn: 47437
diff --git a/llvm/lib/Analysis/IPA/Andersens.cpp b/llvm/lib/Analysis/IPA/Andersens.cpp
index 399ce1f..22f151b 100644
--- a/llvm/lib/Analysis/IPA/Andersens.cpp
+++ b/llvm/lib/Analysis/IPA/Andersens.cpp
@@ -678,7 +678,7 @@
 /// return true.
 ///
 bool Andersens::pointsToConstantMemory(const Value *P) {
-  Node *N = &GraphNodes[FindNode(getNode((Value*)P))];
+  Node *N = &GraphNodes[FindNode(getNode(const_cast<Value*>(P)))];
   unsigned i;
 
   for (SparseBitVector<>::iterator bi = N->PointsTo->begin();