`with_platform_windows` depends on the `platforms` option,
and is an inaccurate proxy check for `host_machine.system() == 'windows'`.
The ICD path and shared library name are dependent on the host system,
not whether or not Lavapipe is built with `WIN32` platform support.
In fact Lavapipe can be built with no platforms (`-Dplatforms=`)
if you only need headless (then this check would be incorrect)
fixes: e030ab5163
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29900>
94379377c4