gdiplus/tests: Skip the tests if unable to load the TIFF image.

[Dmitry Timoshkov]

Francois Gouget <fgouget at codeweavers.com> wrote:

> The goal of the Wine tests is to document the Windows behavior that 
> Windows applications expect.

Skipping a test because your VM is broken doesn't qualify as a documentation
of Windows behaviour.

I don't think that you have resources and intention to have Windows VMs with
all possible pre/post SP/hotfixes configurations. Having just one regualrly
updated one should be more than enough.

-- 
Dmitry.