Prevent stack-use-after-scope (NVIDIA#5572)

Signed-off-by: Joaquin Anton <janton@nvidia.com>

Author: jantonguirao

dali/operators/io/file/file_read.cc

@@ -39,16 +39,15 @@ class FileRead : public StatelessOperator<CPUBackend> {
     filenames_.resize(nsamples);
     files_.resize(nsamples);
     auto &tp = ws.GetThreadPool();
+    FileStream::Options opts;
+    opts.use_mmap = !dont_use_mmap_;
+    opts.use_odirect = use_o_direct_;
+    opts.read_ahead = false;
     for (int i = 0; i < nsamples; i++) {
       size_t filename_len = filepaths.tensor_shape_span(i)[0];
       filenames_[i].resize(filename_len + 1);
       std::memcpy(&filenames_[i][0], filepaths.raw_tensor(i), filename_len);
       filenames_[i][filename_len] = '\0';
-
-      FileStream::Options opts;
-      opts.use_mmap = !dont_use_mmap_;
-      opts.use_odirect = use_o_direct_;
-      opts.read_ahead = false;
       tp.AddWork(
         [&, i](int tid) {
           files_[i] = FileStream::Open(filenames_[i], opts);