lib-storage: When index mkdir() fails with EPERM, create the dir anyway with 0700 mode. This avoids failing entirely when /var/mail/user has 0660 permissions and we don't have access to the group. The error message is still logged.
lib-storage: When index mkdir() fails with EPERM, create the dir anyway with 0700 mode.
This avoids failing entirely when /var/mail/user has 0660 permissions and we
don't have access to the group. The error message is still logged.

jwm/dovecot-notmuch,jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch