fixed typo in spec

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404078

dlib/svm/svm_abstract.h

@@ -73,7 +73,7 @@ namespace dlib
         typename alloc_type1,
         typename alloc_type2
         >
-    const generic_probabilistic_decision_function<typename trainer_type::trained_function_type> 
+    const probabilistic_function<typename trainer_type::trained_function_type> 
     train_probabilistic_decision_function (
         const trainer_type& trainer,
         const std::vector<sample_type,alloc_type1>& x,