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

[Dmitry Timoshkov]

Francois Gouget <fgouget at codeweavers.com> wrote:

> On Windows XP most versions of gdiplus (i.e. older than 5.2) do not support TIFF.

I'd suggest to upgrade the VM instead. Ideally each VM should represent
a Windows version with newest service pack installed it's supposed to run
the tests on, otherwise that VM is useless. IMHO there is no point in
changing the tests to workaround a broken VM state.

-- 
Dmitry.