user32: Skip STM_SETIMAGE message if the static control style doesnot match

[Dmitry Timoshkov]

"Ilya Shpigor" <shpigor at etersoft.ru> wrote:

> This style checking is needed to the STM_SETIMAGE message processing according 
> to MSDN:
> 
> http://msdn.microsoft.com/en-us/library/bb760782%28VS.85%29.aspx

This change requires a test case.

-- 
Dmitry.