bug#79808: Possible missing fclose() in tac_nonseekable (src/tac.c)

Hello coreutils maintainers,

While reviewing the source code of GNU coreutils (tac.c), I noticed a small
resource management
issue in the function `tac_nonseekable()`:

After calling `copy_to_temp(&tmp_stream, &tmp_file, input_fd, file)`, the
function uses `tmp_stream`
in `tac_seekable(fileno(tmp_stream), tmp_file, bytes_copied)` but never
calls `fclose(tmp_stream)` afterwards.
As a result, the FILE stream and its underlying file descriptor remain open
until process termination.

Although this does not cause user-visible problems for short-lived `tac`
executions, adding an explicit
`fclose(tmp_stream)` (and perhaps removing the temporary file) would
improve resource hygiene and
avoid potential descriptor exhaustion if the function were reused in a
long-running context.

Environment:
- Observed in current `src/tac.c` (line ~423 in GNU coreutils latest)

Suggested fix (simplified):
```c
bool ok = tac_seekable(fileno(tmp_stream), tmp_file, bytes_copied);
fclose(tmp_stream);
unlink(tmp_file);
return ok;


  Best regards,
  CheckScope