cross/busybox-static-*: remove
(realized while working on the next big blog post that we can drop this)
The busybox-static packages were used by devices using the obscure "isorec" boot method (that I originally introduced with the samsung-i9100, based on what I saw in the downstream kernel repo at the time IIRC). This method is fairly limited, e.g. we can't append a cmdline easily according to !6917 (merged). After the samsung-i9100 has been switched over to use u-boot in !6921 (merged), all users of busybox-static are now in device/archived/. Let's remove the busybox-static packages so there are less packages we need to sync with Alpine.