mostly backport from upstream https://github.com/open62541/open62541.git

--- qt-everywhere-src-6.9.3/qtopcua/src/3rdparty/open62541/open62541.c.orig
+++ qt-everywhere-src-6.9.3/qtopcua/src/3rdparty/open62541/open62541.c
@@ -123774,7 +123774,7 @@
 UA_StatusCode
 UA_EventLoopPOSIX_setReusable(UA_FD sockfd) {
     int enableReuseVal = 1;
-#ifndef UA_ARCHITECTURE_WIN32
+#ifdef SO_REUSEPORT
     int res = UA_setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
                             (const char*)&enableReuseVal, sizeof(enableReuseVal));
     res |= UA_setsockopt(sockfd, SOL_SOCKET, SO_REUSEPORT,