[test][concurrency] Reenable passing test.

3405691582 · 3405691582 · commit a153d63b5488 · 2021-07-17T01:11:36.000-04:00
Also see #38140; we can remove this XFAIL just like Linux.
diff --git a/test/Concurrency/Runtime/class_resilience.swift b/test/Concurrency/Runtime/class_resilience.swift
@@ -16,7 +16,6 @@
 // UNSUPPORTED: back_deployment_runtime
 
 // XFAIL: windows
-// XFAIL: openbsd
 
 import StdlibUnittest
 import resilient_class
