devel/libepoll-shim: update to 0.0.20200223

• Drop no longer necessary graphics/wayland workaround

Changes: https://github.com/FreeBSDDesktop/epoll-shim/compare/07e2a80...ae12186
Approved by: zeising (x11), grembo (from previous update)
Differential Revision: https://reviews.freebsd.org/D23801