Update fail2ban to 0.9.1.

Version 0.9 is no longer available for downloat at github.
notmuch: Update to 0.19.

This commit also enables manpages.
Merge pull request #4993 from teh/master

Update fail2ban to 0.9.1.
cabal: fix GHC 6.10.4 builds

3e8344d334d42824 added some magic -optP-P flag that the old compiler
version doesn't support.