The event tests hang on FreeBSD

[ghost]

Currently on FreeBSD, when running the test-std test, it hangs at this line:

309/1219 event.channel.test "std-freebsd-x86_64-Debug-bare-multi std.event.Channel"...

Also, @mikdusan on irc said he was able to replicate this issue and he thought it had to do with kevent.

Update: These tests also hang.

310/1218 event.future.test "std-freebsd-x86_64-Debug-bare-multi std.event.Future"...
312/1218 event.lock.test "std-freebsd-x86_64-Debug-bare-multi std.event.Lock"...

[andrewrk]

This issue is blocking #1759

[jethron]

This looks to be odd behaviour in kevent when you specify EV_CLEAR with NOTE_TRIGGER. When you trigger the event with EV_CLEAR, you can't read it back off the queue again, so the next kevent call just blocks forever. Changing this to just EV_ENABLE seems to fix the blocking.

Still doesn't pass all tests though, std.event.Lock test still fails (sometimes, same as Linux, aborts with SIGBUS) and std.event.Channel tests fail most of the time as well, so not sure if this is 100% the correct fix... Future and Group pass consistently, though.