pgsql: Make GiST indexes on-disk compatible with 9.2 again.

Make GiST indexes on-disk compatible with 9.2 again.

The patch that turned XLogRecPtr into a uint64 inadvertently changed the
on-disk format of GiST indexes, because the NSN field in the GiST page
opaque is an XLogRecPtr. That breaks pg_upgrade. Revert the format of that
field back to the two-field struct that XLogRecPtr was before. This is the
same we did to LSNs in the page header to avoid changing on-disk format.

Bump catversion, as this invalidates any existing GiST indexes built on
9.3devel.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/9ee4d06f3fdde37b063b8a0f0fa0a2113ac12303

Modified Files
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src/backend/access/gist/gist.c | 13 ++++++-------
src/backend/access/gist/gistget.c | 2 +-
src/backend/access/gist/gistvacuum.c | 2 +-
src/backend/access/gist/gistxlog.c | 6 +++---
src/include/access/gist.h | 10 +++++++++-
src/include/catalog/catversion.h | 2 +-
src/include/storage/bufpage.h | 30 +++++++++++++++++++-----------
7 files changed, 40 insertions(+), 25 deletions(-)