pgsql: Simplify code in formatting.c now that to upper/lower/initcase do

Log Message:
-----------
Simplify code in formatting.c now that to upper/lower/initcase do not
modify the passed string.

Modified Files:
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pgsql/src/backend/utils/adt:
formatting.c (r1.140 -> r1.141)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/formatting.c?r1=1.140&r2=1.141)