[CMAKE] Fix the bench build for windows

Summary:
Event requires lib ws2_32 on windows (as well as shell32 and advapi32).
The missing ws2_32 caused the bench to fail the build (shell32 and advapi32 are already added by other dependencies).

Test Plan: Run the Gitian builds.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5525