Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party

xz/src/common/mythread.h

+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       mythread.h
+/// \brief      Wrappers for threads
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "sysdefs.h"
+
+
+#ifdef HAVE_PTHREAD
+#       include <pthread.h>
+
+#       define mythread_once(func) \
+        do { \
+                static pthread_once_t once_ = PTHREAD_ONCE_INIT; \
+                pthread_once(&once_, &func); \
+        } while (0)
+
+#       define mythread_sigmask(how, set, oset) \
+                pthread_sigmask(how, set, oset)
+
+#else
+
+#       define mythread_once(func) \
+        do { \
+                static bool once_ = false; \
+                if (!once_) { \
+                        func(); \
+                        once_ = true; \
+                } \
+        } while (0)
+
+#       define mythread_sigmask(how, set, oset) \
+                sigprocmask(how, set, oset)
+
+#endif