Initialize verification_failed in db_stress

tools/db_stress.cc

@@ -547,8 +547,8 @@ class SharedState {
  public:
   static const uint32_t SENTINEL;
 
-  explicit SharedState(StressTest* stress_test) :
+  explicit SharedState(StressTest* stress_test)
-      cv_(&mu_),
+      : cv_(&mu_),
         seed_(FLAGS_seed),
         max_key_(FLAGS_max_key),
         log2_keys_per_lock_(FLAGS_log2_keys_per_lock),
@@ -559,7 +559,8 @@ class SharedState {
         num_done_(0),
         start_(false),
         start_verify_(false),
-      stress_test_(stress_test) {
+        stress_test_(stress_test),
+        verification_failure_(false) {
     if (FLAGS_test_batches_snapshots) {
       fprintf(stdout, "No lock creation because test_batches_snapshots set\n");
       return;