ASTReader.cpp: Fix a warning. [-Wunused-variable]

llvm-svn: 166442
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 4d23ee5..10a4f5e 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1692,6 +1692,7 @@
   case INPUT_FILE: {
     unsigned StoredID = Record[0];
     assert(ID == StoredID && "Bogus stored ID or offset");
+    (void)StoredID;
     off_t StoredSize = (off_t)Record[1];
     time_t StoredTime = (time_t)Record[2];
     bool Overridden = (bool)Record[3];