MFH: r380554

Upgrade to upstream bugfix release 0.64.

This fixes a security bug, various other bugs, and supports SSH
connection sharing between multiple instances of PuTTY and its tools.

Security:	92fc2e2b-c383-11e4-8ef7-080027ef73ec
Security:	CVE-2015-2157
Approved by:	portmgr (erwin)