tests: Skip POSIX-only tests on Windows test-rfifolock and test-vmstate only build on POSIX hosts. Exclude them if building for Windows. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefan Weil <sw@weilnetz.de> Signed-off-by: Andreas Färber <afaerber@suse.de>