no SO_NOSIGPIPE on OpenBSD 
pending https://github.com/zeek/actor-framework/pull/3

Index: auxil/broker/caf/libcaf_net/src/network_socket.cpp
--- auxil/broker/caf/libcaf_net/src/network_socket.cpp.orig
+++ auxil/broker/caf/libcaf_net/src/network_socket.cpp
@@ -42,7 +42,7 @@ uint16_t port_of(sockaddr& what) {
 
 namespace caf::net {
 
-#if defined(CAF_MACOS) || defined(CAF_IOS) || defined(CAF_BSD)
+#if defined(CAF_MACOS) || defined(CAF_IOS) || (defined(CAF_BSD) && !defined(__OpenBSD__))
 #  define CAF_HAS_NOSIGPIPE_SOCKET_FLAG
 #endif
 
