Avoid crashes at shutdown due to printf() in global destructors.

src/util.cpp

@@ -220,8 +220,14 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
         if (fileout)
         {
             static bool fStartedNewLine = true;
-            static boost::mutex mutexDebugLog;
+
-            boost::mutex::scoped_lock scoped_lock(mutexDebugLog);
+            // This routine may be called by global destructors during shutdown.
+            // Since the order of destruction of static/global objects is undefined,
+            // allocate mutexDebugLog on the heap the first time this routine
+            // is called to avoid crashes during shutdown.
+            static boost::mutex* mutexDebugLog = NULL;
+            if (mutexDebugLog == NULL) mutexDebugLog = new boost::mutex();
+            boost::mutex::scoped_lock scoped_lock(*mutexDebugLog);
 
             // reopen the log file, if requested
             if (fReopenDebugLog) {