[Dovecot] Something other than dotlock for uidlist locking?

If I read the code correctly, only dotlocks are supported for locking
of dovecot-uidlist. And I don't see any settings in the config file
for it.

As it turns out, dotlocks are very slow on my system, due to their
implementation via hardlinks.

Would it be possible to support other locking mechanisms for locking
of the uidlist file?

-jdb