Page layout footprint

Hi Heikki,

I'm sorry for lack of explanation. It is my fault.

Heikki says (on commit fest wiki):
------------
I believe I debunked this patch enough already. Apparently there's some
compatibility issue between 32-bit and 64-bit Sparcs, but this patch
didn't catch that. It doesn't seem like this provides any extra safeness
or better error messages. If I'm missing something, please provide more
details on what scenario we currently have a problem, and how this helps
with it.
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The original proposal
(http://archives.postgresql.org/message-id/489FC8E1.9090307@sun.com)
contains two parts. First part is implementation of --footprint cmd line
switch which shows you page layout structures footprint. It is useful
for development (mostly for in-place upgrade) and also for manual data
recovery when you need to know exact structures. Second part was add
this information also into pg_control.file, but how you correctly
mentioned there is not real use case to do it at this moment.

However, there is still --footprint switch which is useful and it is
reason why I put it on wiki for review and feedback. The switch could
also use in build farm for collecting footprints from build farm members.

32/64 bit issue is little bit different story and it is general (not
only SPARC but on SPARC has bigger impact). Problem is that CRC32 gives
probably different result when it is compiled 32bit or 64bit. I'm going
to examine it more.

Zdenek