Fix interval division and multiplication, before:

test=> select '4 months'::interval / 5;
	   ?column?
	---------------
	 1 mon -6 days
	(1 row)

after:

	test=> select '4 months'::interval / 5;
	 ?column?
	----------
	 24 days
	(1 row)

The problem was the use of rint() to round, and then find the remainder,
causing the negative values.

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.132 2005/07/12 16:04:58 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.133 2005/07/20 03:50:24 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2201,7 +2201,7 @@ interval_mul(PG_FUNCTION_ARGS)
 	result->time += (months - result->month) * INT64CONST(30) *
 					USECS_PER_DAY;
 #else
-	result->month = rint(months);
+	result->month = (int)months;
 	result->time = JROUND(span1->time * factor);
 	/* evaluate fractional months as 30 days */
 	result->time += JROUND((months - result->month) * 30 * SECS_PER_DAY);
@@ -2246,7 +2246,7 @@ interval_div(PG_FUNCTION_ARGS)
 					INT64CONST(30) * USECS_PER_DAY) / factor;
 #else
 	months = span->month / factor;
-	result->month = rint(months);
+	result->month = (int)months;
 	result->time = JROUND(span->time / factor);
 	/* evaluate fractional months as 30 days */
 	result->time += JROUND((months - result->month) * 30 * SECS_PER_DAY);