gpgtar: Do not close stderr when calling gpg.

* tools/gpgtar-extract.c (gpgtar_extract): Do not close stderr.
* tools/gpgtar-list.c (gpgtar_list): Ditto.

This is another regression which made it impossible to use use
--status-fd=2 and also swallowed all other stderr output from gpg.

This is somewhat related

• GnuPG-bug-id: T7757