removed some leftover debugging code

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66715 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/image/image.cpp

@@ -976,9 +976,7 @@ void ImageTestCase::CompareSavedImage()
     CPPUNIT_ASSERT( expected24.IsOk() );
     CPPUNIT_ASSERT( !expected24.HasAlpha() );
 
-    unsigned long numColours = expected24.CountColours();
     wxImage expected8 = expected24.ConvertToGreyscale();
-    numColours = expected8.CountColours();
 
 #if wxUSE_PALETTE
     unsigned char greys[256];