dirmngr: Try ldap protocol V3 as fallback
* dirmngr/dirmngr_ldap.c (fetch_ldap): Try V3 Protocol in case default Protocol gives error.
Servers may have blocked V2 Protocol, in which case the
bind will result in a Protocol Error. In that case we try
again with v3 Protocol if the ldap libarary used to compile
dirmngr supports V3.
- Signed-off-by: Andre Heinecke <aheinecke@intevation.de>