comctl32: Fix bitmap size calculation

[Mikołaj Zalewski]

>> Anyway, e.g. Sib Icon Edit required ~ 30 Mb (something like 27 images *
>> 13440 width * 24 height * sizeof(each pixel)) of memory for every instance
>> to run (due to this bug). Now it requires only about 300kb
>>     
>
> Fixing one app doesn't mean it's correct. Yes, there is an obvious error in
> the image list, but you are not just fixing it. You also removing some
> functionality that tool bar depends on.
>   
  The toolbar  doesn't need it anymore - currently after a button size 
change, TOOLBAR_CheckImageListIconSize (called from TOOLBAR_Refresh) 
destroys the imagelist and creates a new one. It seems that even before, 
it was resizing the bitmap using ImageList_SetIconSize (however only 
when no images were added).

Mikołaj