* src/engine-assuan.c (_gpgme_engine_ops_assuan): Add conf_dir.
* src/engine-g13.c (_gpgme_engine_ops_g13): Likewise.
* src/engine-gpg.c (_gpgme_engine_ops_gpg): Likewise.
* src/engine-gpgsm.c (_gpgme_engine_ops_gpgsm): Likewise.
* src/engine-spawn.c (_gpgme_engine_ops_spawn): Likewise.
* src/engine-uiserver.c (_gpgme_engine_ops_uiserver): Likewise.
* src/engine-backend.h (struct engine_ops): Likewise.
* src/engine-gpgconf.c (gpgconf_config_dir_cb, gpgconf_conf_dir):
New functions.
(struct engine_ops): Add gpgconf_conf_dir.
* src/engine.c (_gpgme_engine_op_conf_dir): New function.
* src/engine.h (_gpgme_engine_op_conf_dir): New prototype.
* src/gpgconf.c (gpgme_op_conf_dir): New function.
* src/gpgme.def (gpgme_op_conf_save): New symbol.
* src/gpgme.h.in (gpgme_op_conf_dir): New prototype.
* src/libgpgme.vers (gpgme_op_conf_dir): New symbol.
* tests/gpg/t-gpgconf.c (main): Test gpgme_op_conf_dir.