Give threads a recognisable name to aid in debugging

NOTE: These thread names are visible in gdb when using 'info threads'.
      Additionally both 'top' and 'ps' show these names *unless* told to
      display the command-line instead of task name.

Signed-off-by: Giel van Schijndel <me@mortis.eu>

src/init.cpp

@@ -53,6 +53,10 @@ void Shutdown(void* parg)
 {
     static CCriticalSection cs_Shutdown;
     static bool fTaken;
+
+    // Make this thread recognisable as the shutdown thread
+    RenameThread("bitcoin-shutoff");
+
     bool fFirstThread = false;
     {
         TRY_LOCK(cs_Shutdown, lockShutdown);