pgsql: Fix aboriginal bug in _tarAddFile(): when complaining that the

Log Message:
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Fix aboriginal bug in _tarAddFile(): when complaining that the amount of data
read from the temp file didn't match the file length reported by ftello(),
the wrong variable's value was printed, and so the message made no sense.
Clean up a couple other coding infelicities while at it.

Tags:
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REL8_2_STABLE

Modified Files:
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    pgsql/src/bin/pg_dump:
        pg_backup_tar.c (r1.56.2.2 -> r1.56.2.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_backup_tar.c?r1=1.56.2.2&r2=1.56.2.3)