Changed code to avoid compiler error in visual studio 7.1

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402983

dlib/test/kcentroid.cpp

@@ -653,10 +653,10 @@ namespace
 
 // ----------------------------------------------------------------------------------------
 
-    class kcentroid : public tester
+    class kcentroid_tester : public tester
     {
     public:
-        kcentroid (
+        kcentroid_tester (
         ) :
             tester ("test_kcentroid",
                     "Runs tests on the kcentroid components.")