pgsql-server: Add range-checking in timestamp_recv and timestamptz_recv,

Log Message:
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Add range-checking in timestamp_recv and timestamptz_recv, per
Stephen Frost. Also tighten date range check in timestamp2tm.

Modified Files:
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pgsql-server/src/backend/utils/adt:
timestamp.c (r1.108 -> r1.109)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/adt/timestamp.c.diff?r1=1.108&r2=1.109)