Support out of tree compilation better
Some (downstream) kernel need out of tree compilation to work, like the wiko-lenny2. You could attempt building it in tree, but that leads to a lot of changes to fix import paths.
we could add an option/variable for that, like _kernel_out_dir
for those kernels.
https://gitlab.com/postmarketOS/pmbootstrap/blob/3b240e46f789cd12ff8d7a30febeffea6c21e16c/pmb/config/init.py#L221
This will allow reusing more code, e.g. in downstreamkernel_prepare
should copy the config in this dir instead, and downstreamkernel_package
(pmaports#328 (closed)) should look for the kernel from that dir too. And it will make pmbootstrap kconfig
work for those kernels. (I believe it is broken otherwise, right?)
On the other hand, it would add yet another argument to the downstream_prepare
function.