Makefile:  fix checkout-submodule target
Fix rule generators

Multiple arches broke them
- Enable building in separate directories
- Sort out adding indep packages to PPA
  - BUILD_INDEP_ARCH gets special handling
  - Don't blow away PPA every time; use finesse to add/remove pkgs
- Start of a general framework to debug all these functions; see
  xenomai rules
- Misc formatting
Fix cross-pkg build deps
chroot src pkg config fixes; lots of other bugs fixed

- Fix source package configuration in chroots
  - Several problems with hooks into build and deps on other pkgs :P
- Clean source package before build
  - Needed for Linux, or else a fresh unpack; may break other builds
- Add DEBUG_BUILD to help debug problems with these giant functions
  - Add DEBUG_BUILD to all packages
- Tweak clean rules for various steps
- Fix package path computation
  - Both in general, and in Linux rules
- Misc cleanups