pgsql: When checking for datetime field overflow, we should allow a

Log Message:
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When checking for datetime field overflow, we should allow a fractional-second
part that rounds up to exactly 1.0 second.  The previous coding rejected input
like "00:12:57.9999999999999999999999999999", with the exact number of nines
needed to cause failure varying depending on float-timestamp option and
possibly on platform.  Obviously this should round up to the next integral
second, if we don't have enough precision to distinguish the value from that.
Per bug #4789 from Robert Kruus.

In passing, fix a missed check for fractional seconds in one copy of the
"is it greater than 24:00:00" code.

Broken all the way back, so patch all the way back.

Tags:
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REL8_3_STABLE

Modified Files:
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    pgsql/src/backend/utils/adt:
        datetime.c (r1.184.2.3 -> r1.184.2.4)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/datetime.c?r1=1.184.2.3&r2=1.184.2.4)