This format is now explicitly passed to create_context.

Currently these are always the same, but that doesn't make it right.

This is in the list of allowed formats in the documentation, and some drivers
report this on Windows.

The rectangle count doesn't really matter. If the first rectangle doesn't
cover the entire draw_rect we need to load the depth/stencil surface.

comctl32/tests: Remove variables cx and cy which are not really used from test_approximate_viewrect.