pgsql: Don't include unused space in LOG_NEWPAGE records.

Don't include unused space in LOG_NEWPAGE records.

This is the same trick we use when taking a full page image of a buffer
passed to XLogInsert.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/9e857436ef7dff8fb8a0bf43cfe62650e2be6be9

Modified Files
--------------
src/backend/access/gin/gininsert.c | 4 +-
src/backend/access/gist/gist.c | 2 +-
src/backend/access/heap/heapam.c | 123 ++++++++++++++++++++++-----------
src/backend/access/heap/rewriteheap.c | 6 +-
src/backend/access/nbtree/nbtree.c | 2 +-
src/backend/access/nbtree/nbtsort.c | 2 +-
src/backend/access/spgist/spginsert.c | 6 +-
src/backend/commands/tablecmds.c | 8 ++-
src/backend/commands/vacuumlazy.c | 6 +-
src/include/access/heapam_xlog.h | 10 +--
src/include/access/xlog_internal.h | 2 +-
11 files changed, 109 insertions(+), 62 deletions(-)