st/nine: Handle full pSourceRect better

st/nine: Handle full pSourceRect better

Some apps do set pSourceRect to the full area even if not needed.

Filtering out this case is helpful, as we currently do not handle
properly resizing (pDestRect or window size not of the size of the resource)
when pSourceRect is set. Indeed in this case pSourceRect needs to be modified
before being passed to the presentation backend.

Signed-off-by: Axel Davy <davyaxel0@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5015>