gnome-base/gconf-2.22.0 should USE-depend on openldap. Having ldap USE-flag enabled and openldap not installed fails during configure: checking ldap.h usability... no checking ldap.h presence... no checking for ldap.h... no checking for ldap_ntlm_bind... no configure: error: *** LDAP support explicitely requested but not found ***
it seems this was missed during migration from overlay to the tree. Added it back, thanks for reporting.