Comment 16 for bug 633667

Here is the OpenSUSE patch:

https://build.opensuse.org/package/view_file?file=debugsubpkg.diff&package=rpm&project=openSUSE%3AFactory

It looks like they disabled the %debug_package macro and added code to rpmbuild itself that, after writing out a binary subpackage, reads back its file list and gathers up the corresponding debuginfo files and build-id symlinks into a debuginfo subpackage. That's probably the most reasonable approach if one is willing to modify the C code.