gpg: Add --list-gcrypt-config and "curve" item for --list-config.
* common/openpgp-oid.c (curve_supported_p): New. (openpgp_enum_curves): New. * common/t-openpgp-oid.c (test_openpgp_enum_curves): New. (main): Add option --verbose. * g10/gpg.c (opts): Add --list-gcrypt-config. (list_config): Add items "curve" and "curveoid". Remove unused code.
- GnuPG-bug-id: T1917
- Signed-off-by: Werner Koch <wk@gnupg.org>