remove minimal linux kernel headers these were at best of limited usefulness (for bootstrapping new systems, mainly) and at worst caused real kernel headers to get overwritten when upgrading libc. in case they're needed by anyone, the exact same files are now available in a new git repository: git://git.etalabs.net/mini-lkh
some linux headers useful from user apps. i'm still not sure whether it's a good idea to include or use any of these, but i'll add them for now. it may make more sense to just add official kernel headers to the include path for compiling programs that need them.