Update security/putty to 0.71 security fix release

Unfortunately, this new release breaks GSSAPI_NONE, which is removed
for now. Bug has been reported upstream.

Changelog: https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html

MFH: 2019Q1
Security: 46e1ece5-48bd-11e9-9c40-080027ac955c