pgsql: Remove unnecessary parentheses in assignments.

Log Message:
-----------
Remove unnecessary parentheses in assignments.
Add spaces where needed.
Reference time interval variables as tinterval.

Modified Files:
--------------
pgsql/src/backend/utils/adt:
acl.c (r1.119 -> r1.120)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/acl.c.diff?r1=1.119&r2=1.120)
cash.c (r1.64 -> r1.65)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/cash.c.diff?r1=1.64&r2=1.65)
date.c (r1.114 -> r1.115)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/date.c.diff?r1=1.114&r2=1.115)
datetime.c (r1.153 -> r1.154)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/datetime.c.diff?r1=1.153&r2=1.154)
nabstime.c (r1.137 -> r1.138)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/nabstime.c.diff?r1=1.137&r2=1.138)
selfuncs.c (r1.186 -> r1.187)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/selfuncs.c.diff?r1=1.186&r2=1.187)
timestamp.c (r1.135 -> r1.136)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/timestamp.c.diff?r1=1.135&r2=1.136)
varlena.c (r1.128 -> r1.129)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/varlena.c.diff?r1=1.128&r2=1.129)