46640 Patch #1454481:  Make thread stack size runtime tunable.
46647 Markup fix

The first is causing many buildbots to fail test runs, and there
are multiple causes with seemingly no immediate prospects for
repairing them.  See python-dev discussion.

Note that a branch can (and should) be created for resolving these
problems, like

svn copy svn+ssh://svn.python.org/python/trunk -r46640 svn+ssh://svn.python.org/python/branches/NEW_BRANCH

followed by merging rev 46647 to the new branch.

(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.)