[dovecot] 0.99.9-test6

[Timo Sirainen]

Just two fixes:

- dovecot-uidlist file is now assumed to be changed if it's modify time
is changed. before we relied on inode changing which isn't fully
reliable.
- mbox dotlocks sometimes incorrectly thought someone else had
overridden them

Known problems that I should fix:

- mbox: we don't necessarily notice message flag changes by external
programs (or another dovecot without index files). It's because we don't
always reparse the whole mbox file when it has changed. I think I'll
have to add some X-IMAP-Changelog header which describes what changes
were made by other Dovecot processes. If the change isn't listed in that
header, we'll fallback to reparsing the whole file. Although that's
still a bit annoying since MTA just appends the new mails, we wouldn't
really need to reparse the whole file then, just the new mails.
- I should use link() instead of relying on O_EXCL which doesn't work
with NFSv2 (or Linux's NFSv3 client).
- .subscriptions and .customflags files still aren't NFS-safe