adds riscv arch and a bugfix for swab.h, which is included by objtool in recent kernel builds from the host.
http://ftp.barfooze.de/pub/sabotage/tarballs/linux-headers-4.19.88-2.tar.xz
$ sha256sum linux-headers-4.19.88-2.tar.xz
dc7abf734487553644258a3822cfd429d74656749e309f2b25f09f4282e05588 linux-headers-4.19.88-2.tar.xz
$ sha512sum linux-headers-4.19.88-2.tar.xz
e3d644642eac8d8e9e356a937a67a887d4b11700b59304b2d9bd1d7c27e1172982480f31342144abf4ab86a5ecb45dd4394d995ff3aae0586948fcf5fab73982 linux-headers-4.19.88-2.tar.xz