[Libguestfs] Splitting the large libguestfs repo

I got a little way into this. The two attached patches are preliminary work. My proposed split is: libguestfs.git common -> git submodule libguestfs-common.git generator/ lib/ all language bindings C based tools (eg. virt-df, virt-edit, guestfish) guestfs-tools.git common -> git submodule libguestfs-common.git virt-builder, virt-customize, virt-sparsify, virt-sparsify, etc virt-v2v.git common -> git submodule libguestfs-common.git virt-p2v.git [already done] The current common/ subdirectory would become a git submodule. While git submodules are awkward, they do solve this particular problem with having common code shared across the repositories, there's only one git submodule and it's under our control. It does mean that any time there's a change to common/, we would need to add a commit to the other 3 repos updating the submodule hash. There are only 6 generated files which are not confined to the new libguestfs.git. 4 files are needed by virt-customize and 2 by virt-v2v (and these last 2 will probably go away in future). My proposal (in patch 2/2) is that we simply copy these 6 files into the common submodule. It's not very elegant but it only affects a tiny fraction of all generated files, these ones are updated very infrequently, and it solves the problem for now. A possible future path would be to split the generator so there's a mini-generator for virt-customize. libguestfs-common.git can be created from libguestfs.git using 'git filter-branch --prune-empty --subdirectory-filter common master'. I tested this already and it seems to work. The two other new repos can be created using the rather more complex technique described here which I didn't try yet: https://stackoverflow.com/questions/2797191/how-to-split-a-git-repository... Previous discussion was in this thread over several months: https://www.redhat.com/archives/libguestfs/2018-February/thread.html#00067 https://www.redhat.com/archives/libguestfs/2019-April/thread.html#00260 https://www.redhat.com/archives/libguestfs/2019-June/thread.html#00095 https://www.redhat.com/archives/libguestfs/2019-July/thread.html#00000 Rich.