gpgme_set_include_certs specifies how many
certificates should be included in an S/MIME signed message. By
default, only the sender’s certificate is included. The possible
values of nr_of_certs are:
Fall back to the default of the crypto backend. This is the default for GPGME.
Include all certificates except the root certificate.
Include all certificates.
Include no certificates.
Include the sender’s certificate only.
Include the first n certificates of the certificates path, starting
from the sender’s certificate. The number
n must be positive.
Values of nr_of_certs smaller than -2 are undefined.
This option is only relevant to the CMS crypto engine, and ignored by all other engines.
gpgme_get_include_certs returns the number of
certificates to include into an S/MIME signed message.