mail/mutt: Update to 1.9.5

Changelog:

• GPGME S/MIME non-detached signature handling.

• A compilation issue with ncurses-6.1 when tinfow is split out. Hopefully the fix doesn't impact anyone: please let me know of any issues.

• Regular expression crashes and weird behavior problems on MacOS (and possibly other BSDs). This was most noticeable with the recent Xcode 9.3 release, but the issue has existed for a while.

• GSSAPI authentication issues, which may have affected Exchange users. We've changed behavior to match the RFC. If you are negatively impacted by this, please let me know.

PR: 227519
Submitted by: dereks@lifeofadishwasher.com (maintainer)