Fixed a compile time error that happens on debian's gcc 4.1.2

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404204

dlib/svm/function.h

@@ -779,7 +779,8 @@ namespace dlib
             // Rather than doing something like, best_idx = index_of_max(weights*x-b)
             // we do the following somewhat more complex thing because this supports
             // both sparse and dense samples.
-            using sparse_vector::dot;
+            using dlib::sparse_vector::dot;
+            using dlib::dot;
             scalar_type best_val = dot(rowm(weights,0),x) - b(0);
             unsigned long best_idx = 0;
 

dlib/svm/svm_c_linear_trainer.h

@@ -164,7 +164,8 @@ namespace dlib
                 - for all i: #dot_prods[i] == dot(colm(#w,0,w.size()-1), samples(i)) - #w(w.size()-1)
         !*/
         {
-            using sparse_vector::dot;
+            using dlib::sparse_vector::dot;
+            using dlib::dot;
             for (long i = 0; i < samples.size(); ++i)
                 dot_prods[i] = dot(colm(w,0,w.size()-1), samples(i)) - w(w.size()-1);
 

dlib/svm/svm_multiclass_linear_trainer.h

@@ -83,7 +83,8 @@ namespace dlib
             // figure out which label is the best
             for (unsigned long i = 0; i < distinct_labels.size(); ++i)
             {
-                using sparse_vector::dot;
+                using dlib::sparse_vector::dot;
+                using dlib::dot;
                 // perform: temp == dot(relevant part of current solution, samples[idx]) - current_bias
                 scalar_type temp = dot(rowm(current_solution, range(i*dims, (i+1)*dims-2)), samples[idx]) - current_solution((i+1)*dims-1);