pgsql: Fix (hopefully for the last time) problems with datetime values

Log Message:
-----------
Fix (hopefully for the last time) problems with datetime values displaying
like '23:59:60' because of fractional-second roundoff problems. Trying
to control this upstream of the actual display code was hopeless; the right
way is to explicitly round fractional seconds in the display code and then
refigure the results if the fraction rounds up to 1. Per bug #1927.

Modified Files:
--------------
pgsql/src/interfaces/ecpg/pgtypeslib:
dt.h (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/dt.h.diff?r1=1.31&r2=1.32)
dt_common.c (r1.29 -> r1.30)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/dt_common.c.diff?r1=1.29&r2=1.30)
interval.c (r1.28 -> r1.29)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/interval.c.diff?r1=1.28&r2=1.29)
timestamp.c (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/timestamp.c.diff?r1=1.31&r2=1.32)
pgsql/contrib/btree_gist:
btree_ts.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_ts.c.diff?r1=1.10&r2=1.11)
pgsql/src/backend/utils/adt:
date.c (r1.120 -> r1.121)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/date.c.diff?r1=1.120&r2=1.121)
datetime.c (r1.157 -> r1.158)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/datetime.c.diff?r1=1.157&r2=1.158)
timestamp.c (r1.153 -> r1.154)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/timestamp.c.diff?r1=1.153&r2=1.154)
pgsql/src/include/utils:
date.h (r1.30 -> r1.31)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/date.h.diff?r1=1.30&r2=1.31)
timestamp.h (r1.55 -> r1.56)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/timestamp.h.diff?r1=1.55&r2=1.56)