Thread: pgsql: Fix to_char(interval) to return proper year and century values.

Log Message:
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Fix to_char(interval) to return proper year and century values.
Fix to_char(interval) to return large year/month/day/hour values that
are larger than possible timestamp values.
Prevent to_char(interval) format specifications that make no sense, like
Month.
Clean up formatting.c code to more logically handle return lengths.

Modified Files:
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    pgsql/src/backend/utils/adt:
        formatting.c (r1.97 -> r1.98)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/formatting.c.diff?r1=1.97&r2=1.98)