git: cbc620a473ce..5223d1d95fdd - vendor/libevent - vendor branch updated

[Cy Schubert]

The branch vendor/libevent has been updated by cy:

URL: https://cgit.FreeBSD.org/src/log/?id=cbc620a473ce..5223d1d95fdd

5223d1d95fdd libevent: Import libevent 2.1.12