After updating openldap to 2.4.43 I received the following error:
/etc/openldap/slapd.conf: line 120: smbk5pwd: <smbk5pwd-enable> module "smbk5pwd-enable" only allowed when compiled with -DDO_SAMBA.
slapadd: bad configuration file!
It appears the behavior of USE=smbkrb5passwd changed between the last stable version and the current one. Previously all methods in smbkrb5passwd were implicitly enabled with USE=smbkrb5passwd. Now, Kerberos and Samba support in smbkrb5passwd each (logically) require their corresponding use flags as well.
I recommend some type of info or pkg_setup warning of the change in USE flag behavior, particularly for users upgrading.