TQPrinterPrivate: add virtual destructor.

As derivative from it e.g. TQPrinterUnixPrivate are getting deleted (e.g
in unix TQPrinter implementation) by a reference to base class.

Also added missing include to the header.

Signed-off-by: Alexander Golubev <fatzer2@gmail.com>

src/kernel/qprinter_p.h

@@ -43,6 +43,7 @@
 #ifndef TQT_NO_PRINTER
 
 #ifndef QT_H
+#include <ntqprinter.h>
 #include <ntqshared.h>
 #include <ntqstring.h>
 #include <ntqsize.h>
@@ -53,6 +54,8 @@ class TQPrinterPrivate
 public:
     TQ_UINT32 printerOptions;
     TQPrinter::PrintRange printRange;
+
+    virtual ~TQPrinterPrivate() {};
 };
 
 #endif