Support Brainpoolp512r1 certs specified with ECDomainParameters.

* src/keyinfo.c (ecdomainparm_to_name): New table.
(_ksba_keyinfo_to_sexp): Support ECDomainParameter lookup.

Note that in contrast to SEC1 PKIX does no allow specification of a
curve via domain parameters - but it has anyway been seen in the wild.
Thus we add some limited support.

• Signed-off-by: Werner Koch <wk@gnupg.org>