pgsql: Use better named loop variable for large loop, rather than 'i'.

Log Message:
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Use better named loop variable for large loop, rather than 'i'.

Modified Files:
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pgsql/src/backend/tcop:
postgres.c (r1.494 -> r1.495)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.494&r2=1.495)