contrib: bump opendht and fix uwp build

Bump OpenDHT to commit 09b4e71d (30/03/2017) to fix various bugs since
last bump and to add new API to fix issues with certificate memory
management.

This includes a patch for UWP to build this new version.

Change-Id: I80dc2aa5113a394b725764fa6c71b35b4b18a853
Tuleap: #1548
Reviewed-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>