[lazarus] win32 interface: CheckListBox memleak.

[Vincent Snijders]

Hi,

I investigated why sometimes the ItemRecords of a checklistbox aren't
freeed. What happens is, that the LCL sends a LM_DESTROY message to the
interface for the checklistbox. The interface removes the Lazarus
property from the checklistbox window. Therefore when the windows is
destroyed and the WM_DESTROY message is received, the owner object is
nil and we don't know what (type) the original lcl object was.

I propose that we remove the line (around line 583 of win32object.inc)
  RemoveProp(Handle, 'Lazarus');

Then when the WM_DESTROY message is received in the windows procedure,
there is still a owner object. 

The Lazarus property will be removed by the enumprops call later in the
WM_DESTROY handling code.

Regards,
Vincent.