(thanks to Neal for review)

s_unpack_from to PyCFunction.

the right compiler flags.

- Following Guido's comments, renamed

  * pack_to -> pack_into
  * recv_buf -> recv_into
  * recvfrom_buf -> recvfrom_into

- Made fixes to _struct.c according to Neal Norwitz comments on the checkins
  list.

- Converted some ints into the appropriate -- I hope -- ssize_t and size_t.

2*sizeof(size_t) now, not 8.  This probably accounts for
current disasters on the 64-bit buildbot slaves.

to each allocated block.  This was using 4 bytes for each such
piece of info regardless of platform.  This didn't really matter
before (proof: no bug reports, and the debug-build obmalloc would
have assert-failed if it was ever asked for a chunk of memory
>= 2**32 bytes), since container indices were plain ints.  But after
the Py_ssize_t changes, it's at least theoretically possible to
allocate a list or string whose guts exceed 2**32 bytes, and the
PYMALLOC_DEBUG routines would fail then (having only 4 bytes
to record the originally requested size).

Now we use sizeof(size_t) bytes for each of a PYMALLOC_DEBUG
build's extra debugging fields.  This won't make any difference
on 32-bit boxes, but will add 16 bytes to each allocation in
a debug build on a 64-bit box.

not sure that's really standard compliant behaviour, but I guess
we have to fix that anyway...

Fix by renaming the variable.

In a different module, Neal fixed it by renaming _self to self.  There's
already a variable named 'self' here, so I used selfptr.

(I'm committing this on a Mac without Tk, but it's a simple search-and-replace.
<crosses fingers>, so  I'll watch the buildbots and see what happens.)

the output required more than one line.  "Small" dicts got
displayed in seemingly random order (the hash-induced order
produced by dict.__repr__).  None of this was documented.
Now pprint functions always sort dicts by key, and the docs
promise it.

This was proposed and agreed to during the PyCon 2006 core
sprint -- I just didn't have time for it before now.