- Change pkg-config file to use ${prefix}/include

rather thant ${prefix}/include/sgpemv2: users will
be able to use directives like "#include <sgpemv2/scheduler.hh>"
in their headers, which reduces name clashes.
- Make _mutex a protected member of Singleton, so that
inheriters can recycle it :-)
- Add exclusive access control for step_forward()
- Add two states (future and exhausted) to Request


git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@707 3ecf2c5c-341e-0410-92b4-d18e462d057c

src/templates/singleton.hh

@@ -44,10 +44,12 @@ namespace sgpem
      * \return The instantiated object
      */
     static Instantiated_class& get_instance();
+    
+  protected:
+    static Glib::StaticMutex SG_DLLLOCAL _mutex;
 
   private:
     static Instantiated_class* _instance;
-    static Glib::StaticMutex   SG_DLLLOCAL _mutex;
   }
   ; //~ class Singleton