Fixed a bug in any_function which prevented the .get() function

from compiling.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404138

dlib/any/any_function_impl.h

@@ -310,6 +310,7 @@ static typename disable_if<is_function<T>,const T&>::type deref (const U& item)
 
 #define DLIB_ANY_FUNCTION_DERIVED_BOILERPLATE               \
     typename funct_type<T>::type item;                      \
+    derived() {}                                            \
     derived(const T& val) : item(copy(val)) {}              \
     virtual void copy_to ( scoped_ptr<base>& dest) const    \
     { dest.reset(new derived(deref<T>(item))); }