update header cache database

[gerazov]

Thanks to the tip of @flatcap in issue https://github.com/neomutt/neomutt/issues/3919 I've updated my muttrc to use lmdb instead of the kyotocabinet (default?) and there is a huge difference :exploding_head:

Changing folders and mailboxes is now blazingly fast :zap:

[Tokariew]

NeoMutt 20191207
Copyright (C) 1996-2016 Michael R. Elkins and others.
NeoMutt comes with ABSOLUTELY NO WARRANTY; for details type 'neomutt -vv'.
NeoMutt is free software, and you are welcome to redistribute it
under certain conditions; type 'neomutt -vv' for details.

System: Linux 5.15.0-79-generic (x86_64)
ncurses: ncurses 6.2.20200212 (compiled with 6.2.20200212)
libidn: 1.33 (compiled with 1.33)
GPGme: 1.13.1-unknown
libnotmuch: 5.2.0
hcache backends: tokyocabinet

What if my neomutt doesn't have builtin lmdb? Ubuntu 20.04 don't have builtin lmdb. And with this option added i got errors on each opening of neomutt