gpg: Emit compatible Ed25519 signature.
* g10/pkglue.c (sexp_extract_param_sos_nlz): New. * g10/pkglue.h: Add the declaration. * g10/sign.c (do_sign): Use sexp_extract_param_sos_nlz for Ed25519.
Ed25519 signature in GnuPG 2.2 has no leading zeros.
- GnuPG-bug-id: T5331
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>