pgsql: Use 0-based numbering in comments about backup blocks.

Use 0-based numbering in comments about backup blocks.

The macros and functions that work with backup blocks in the redo function
use 0-based numbering, so let's use that consistently in the function that
generates the records too. Makes it so much easier to compare the
generation and replay functions.

Backpatch to 9.0, where we switched from 1-based to 0-based numbering.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/42279b291a2de8e4bd5ecaf4f8214337e4b0c936

Modified Files
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src/backend/access/nbtree/nbtinsert.c |   10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)