Don't assume tarball is part of URL; fixes for building arch-indep pkgs

- URL now completely constructed in pkg config makefiles
- Some fixes for building arch-indep pkgs
  - Allow build-binary-package target to be ARCH = INDEP
  - Pick the arch-indep chroot for building
- Fix location of lib* packages in PPA
Add hostmot2-firmware package; disabled

Package Build-Depends: ghdl doesn't exist in Debian, so package is
disabled.
Linux pkg rules:  clean up source pkg config script args
Fixes RTAI package builds

- Kernel submodule updates:
  - Fix RTAI kernel config
  - Fix RTAI pkg config rules
  - Re-enable RTAI by default
  - Extra debug output
  - Clean up unnecessary tarball unpack
  - Bump release
- Remove git/rtai submodule:  now building from tarball
- Re-enable RTAI build
- Fix build with RTAI tarball as extra Debian upstream source
- RTAI submodule updates
  - Re-add missing autoconf files
  - Bump release
- Bump Linux package release
Set update-chroot-deps as SQUEAKY clean target

Too annoying to rebuild
Add $DISTDIR to bindmounts list for chroot src pkg configuration

RTAI source tarball copied there