Fix testgdi

The testgdi program makes GDI+ calls without invoking
GdiplusStartup().

This fixes the following errors:

got st: 3 expected Okgot st: 2 expected Okjpg drawn
got st: 3 expected Okgot st: 2 expected Oktif drawn
got st: 3 expected Okgot st: 2 expected Okgif drawn
got st: 3 expected Okgot st: 2 expected Okpng drawn
got st: 3 expected Okgot st: 2 expected Okbmp drawn
Merge pull request #16 from ranma42/fix-testgdi

Fix testgdi