Switched the dlog and tp objects so that their destruction orders

are safer.  This only matters if the user were to modify the example
such that tasks were still running after main() ends.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402839

examples/thread_pool_ex.cpp

@@ -15,11 +15,6 @@
 
 using namespace dlib;
 
-
-// Here we make an instance of the thread pool object
-thread_pool tp(3);
-
-
 // We will be using the dlib logger object to print out messages in this example
 // because its output is timestamped and labeled with the thread that the log
 // message came from.  So this will make it easier to see what is going on in 
@@ -27,6 +22,11 @@ thread_pool tp(3);
 // documentation and examples for detailed information regarding its use.
 logger dlog("main");
 
+
+// Here we make an instance of the thread pool object
+thread_pool tp(3);
+
+
 // ----------------------------------------------------------------------------------------
 
 class test