Fixed -Werror=unused-but-set-variable in thread_status_impl

Summary:
Fixed -Werror=unused-but-set-variable in thread_status_impl

util/thread_status_impl.cc

@@ -68,8 +68,7 @@ Status ThreadStatusImpl::GetThreadList(
         std::memory_order_relaxed);
     auto cf_key = thread_data->cf_key.load(
         std::memory_order_relaxed);
-    auto iter = cf_info_map_.find(
-        thread_data->cf_key.load(std::memory_order_relaxed));
+    auto iter = cf_info_map_.find(cf_key);
     assert(cf_key == 0 || iter != cf_info_map_.end());
     auto* cf_info = iter != cf_info_map_.end() ?
         iter->second : nullptr;

util/thread_status_impl_debug.cc

@@ -16,7 +16,7 @@ void ThreadStatusImpl::TEST_VerifyColumnFamilyInfoMap(
   assert(cf_info_map_.size() == handles.size());
   for (auto* handle : handles) {
     auto* cfd = reinterpret_cast<ColumnFamilyHandleImpl*>(handle)->cfd();
-    auto iter = cf_info_map_.find(cfd);
+    auto iter __attribute__((unused)) = cf_info_map_.find(cfd);
     assert(iter != cf_info_map_.end());
     assert(iter->second);
     assert(iter->second->cf_name == cfd->GetName());