dirmngr is part of GnuPG project. It used to live in a separated tree from GnuPG itself.
The last GPLv2 release is 1.0.3 from the separate tree. Version control of separated
tree is not available anymore. Tarball was downloaded from ftp://ftp.gnupg.org/gcrypt/dirmngr

The tarball was signed with a key that is not available anymore. Current signing keys
of the GnuPG project are listed in https://www.gnupg.org/signature_key.html

The dirmngr_ldap executable was disabled by a commit, modifying the configure not to fail
on ldap detection, and also src/Makefile.in not to build and install dirmngr_ldap.
Currently this executable is not required for Mer purposes and avoid to add a dependency
on openldap.