$OpenBSD$

Index: runtime/druntime/src/core/sys/openbsd/pthread_np.d
--- runtime/druntime/src/core/sys/openbsd/pthread_np.d.orig
+++ runtime/druntime/src/core/sys/openbsd/pthread_np.d
@@ -0,0 +1,19 @@
+/**
+ * D header file for OpenBSD.
+ */
+module core.sys.openbsd.pthread_np;
+
+version (OpenBSD):
+extern (C) nothrow @nogc:
+
+public import core.sys.posix.sys.types;
+import core.sys.posix.signal : stack_t;
+
+alias pthread_switch_routine_t = void function(pthread_t, pthread_t);
+
+int pthread_mutexattr_getkind_np(pthread_mutexattr_t);
+int pthread_mutexattr_setkind_np(pthread_mutexattr_t *, int);
+void pthread_set_name_np(pthread_t, const(char)*);
+int pthread_stackseg_np(pthread_t, stack_t*);
+int pthread_main_np();
+
