ports/182146: Update mail/gmime26 to 2.6.18

[wg at FreeBSD.org]

Synopsis: Update mail/gmime26 to 2.6.18

Responsible-Changed-From-To: freebsd-ports-bugs->wg
Responsible-Changed-By: wg
Responsible-Changed-When: Tue Sep 17 21:50:05 UTC 2013
Responsible-Changed-Why: 
I'll take it.

http://www.freebsd.org/cgi/query-pr.cgi?pr=182146