Fix warnings produced by g++ on Windows.

src/IceCfgNode.cpp

Index: src/IceCfgNode.cpp
diff --git a/src/IceCfgNode.cpp b/src/IceCfgNode.cpp
index 095994ee920d0cd929a3b77e0d8cbae545950136..d57224b9f14a2949e5aa5f04061114054eab42eb 100644
--- a/src/IceCfgNode.cpp
+++ b/src/IceCfgNode.cpp
@@ -241,6 +241,7 @@ CfgNode *CfgNode::splitIncomingEdge(CfgNode *Pred, SizeT EdgeIndex) {
     }
   }
   assert(Found);
+  (void)Found;
   // Repoint this node's in-edge.
   Found = false;
   for (CfgNode *&I : InEdges) {
@@ -252,12 +253,14 @@ CfgNode *CfgNode::splitIncomingEdge(CfgNode *Pred, SizeT EdgeIndex) {
     }
   }
   assert(Found);
+  (void)Found;
   // Repoint all suitable branch instructions' target and return.
   Found = false;
   for (Inst &I : Pred->getInsts())
     if (!I.isDeleted() && I.repointEdges(this, NewNode))
       Found = true;
   assert(Found);
+  (void)Found;
   return NewNode;
 }