Silence unused-variable warning when assertions are disabled.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156091 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index 6e93030..a171a06 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -538,6 +538,7 @@
     void markFallthroughVisited(const AttributedStmt *Stmt) {
       bool Found = FallthroughStmts.erase(Stmt);
       assert(Found);
+      (void)Found;
     }
 
     typedef llvm::SmallPtrSet<const AttributedStmt*, 8> AttrStmts;