qcrypto/core: add generic infrastructure for crypto options amendment

This will be used first to implement luks keyslot management.

block_crypto_amend_opts_init will be used to convert
qemu-img cmdline to QCryptoBlockAmendOptions

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-2-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/block/crypto.h b/block/crypto.h
index b935695..06e044c 100644
--- a/block/crypto.h
+++ b/block/crypto.h
@@ -91,6 +91,9 @@
 QCryptoBlockCreateOptions *
 block_crypto_create_opts_init(QDict *opts, Error **errp);
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp);
+
 QCryptoBlockOpenOptions *
 block_crypto_open_opts_init(QDict *opts, Error **errp);