This is a sandbox module to test if our build setup for external libraries
(for example FFmpeg) is sane.

What we are trying to achieve:

satisfy:
  patching of CVS checkout using our patch files placed in our CVS

  passing of
    make
    make distcheck
    non-srcdir build (ie, mkdir build; cd build; ../configure; make)

How it works:

* configure checks whether or not it should update ffmpeg from CVS by looking
  at the nano version number
  - if it's 1, we're in cvs mode, and it should check it out
  - if it's not 1, we're in prerel or rel mode, and the code should already
    be on disk
    FIXME: we could change this to really check out the source code if some
    required files aren't there just in case someone checks out from CVS
    but CVS is not at nano 1

* patching of the checked-out copy happens at

Axioms under which we work:
- the dist tarball needs to include either
  - the pristine ffmpeg checkout + our patches + a patch mechanism on make
  or
  - the ffmpeg checkout with patches already applied

- configure/make is not allowed to touch files that already live in the source
  tree; if they need to then they need to be copied first and cleaned
  afterward

- it would be very nice if, on update of either the Tag file or the patch set,
  make would know exactly what to do with it.