Fix FTBFS with GCC6

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit d01e804f0f)

kbarcode/tec.cpp

@@ -67,14 +67,14 @@ TQString tec452(const TQString &url, int count, const TQString &art, const TQStr
 
     TQFile f( filename );
     if ( !f.open( IO_ReadOnly ) )
-        return false;
+        return 0;
 
     //clearLabel();
 
     TQDomDocument doc( "KBarcodeLabel" );
     if ( !doc.setContent( &f ) ) {
         f.close();
-        return false;
+        return 0;
     }
     f.close();