mail/exim: attempt to fix *taint* and auth issues
Bump PORTREVISION for master port to force all slaves rebuild
Drop PORTREVISION for exim-postgresql slave in favor of master settings
Adopt recent commits from Exim repo as numerated extra-patches till new maintenance release will be published:
- SPF: fix result for case of only non-spf TXT RRs
- Fix error logging for dynamically-loaded modules
- heimdal auth: fix the increase of big_buffer size
- Taint: hybrid checking mode
- Fix taint hybrid-checking on BSD
- TFO: even in binary built for modern Linux, handle error returned by old Linux kernel
- Taint: slow-mode checking only
- Auths: fix cyrus-sasl driver for gssapi use
- GnuTLS: fix hanging callout connections