MFH: r436313 r436321 r436323

Update to new upstream release 0.68 (security fixes)

Additional minor updates on top of cy@'s patch (USE_GNOME, USE_XORG,
LDFLAGS).

ChangeLog: http://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html

[436321]
Add forgotten patch for Linux -> BSD portability.

[436323]
Remove leftover files.

The reference to these had been removed as of r184036 on 2007-02-03 already.

Submitted by: cy@
Security: CVE-2017-6542
Security: 9b973e97-0a99-11e7-ace7-080027ef73ec
Differential Revision: https://reviews.freebsd.org/D10023

Approved by: ports-secteam@ (junovitch@)