bpo-37087: Adding native ID support for OpenBSD (GH-13654)

diff --git a/Include/pythread.h b/Include/pythread.h
index c0f1eb9..84b79c8 100644
--- a/Include/pythread.h
+++ b/Include/pythread.h
@@ -26,7 +26,7 @@
 PyAPI_FUNC(void) _Py_NO_RETURN PyThread_exit_thread(void);
 PyAPI_FUNC(unsigned long) PyThread_get_thread_ident(void);
 
-#if defined(__APPLE__) || defined(__linux__) || defined(__FreeBSD__) || defined(_WIN32)
+#if defined(__APPLE__) || defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(_WIN32)
 #define PY_HAVE_THREAD_NATIVE_ID
 PyAPI_FUNC(unsigned long) PyThread_get_thread_native_id(void);
 #endif