gdiplus/tests: Fix region leak (Coverity).

Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com>
Signed-off-by: Vincent Povirk <vincent@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/gdiplus/tests/graphics.c

@@ -2194,6 +2194,7 @@ static void test_clip_xform(void)
     expect(0xff, color);
 
     GdipDeleteGraphics(graphics);
+    GdipDeleteRegion(clip);
     ReleaseDC(hwnd, hdc);
 }