Thanks Eric, Antoine and Mark.

I'm attaching two new patches: a replacement patch for cpython, and a new patch for the devguide

I've moved the docs to the dev guide, starting a new "Debugging and Instrumentation" section there.

Changes to the cpython patch:
  * fixed a bug in configure.in that was enabling systemtap support even without --with-systemtap (if the devel toolchain was present)
  * I added an initial check to test_systemtap to skip the tests unless Python was configured --with-systemtap
  * pysystemtap.h is not meant to be public, so I've moved the source pysystemtap.d and generated header pysystemtap.h from Include/ to Python/.  I also simplified pysystemtap.d (removed the #pragma lines, since I believe they're DTrace-specific).
  * I've introduced a Python/ceval_systemtap.h private header as suggested by Antoine, moving things in there to simplify the changes to Python/ceval.c

Changes to the devguide docs:
  * removed the ".. impl-detail" as this only seems to work (and be appropriate) in the cpython Doc build, not in devguide.
  * added "eu-readelf -n" example from Mark

The docs refer to the low-level way of doing things (using the markers directly), but don't yet spell out the higher-level way (creating a tapset).  I've left this out of the patches for now to keep the patches simpler.