Improve dead store diagnostic.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@49711 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/DeadStores.cpp

@@ -166,7 +166,7 @@ public:
   }
   
   virtual const char* getDescription() const {
-    return "Value stored to variable is never used.";
+    return "Value stored to variable is never subsequently read.";
   }
   
   virtual void EmitWarnings(BugReporter& BR) {