Fixed tdebase FTBFS caused by commit 427ebd3 when compiling with NDEBUG.

Commit 427ebd3 remove the definition of NDEBUG if kdebug.h is included in the
compilation process. If such file is incluced in a .cpp file and not in the
corresponding .h file, FTBFS happens due to different class interface between the
class declaration and class definition.

tdecore/kdebug.h

@@ -25,8 +25,6 @@
 #include <tqstring.h>
 #include "tdelibs_export.h"
 
-#undef NDEBUG
-
 class TQWidget;
 class TQDateTime;
 class TQDate;