pgsql: Make the MONEY data type have a thousands separator != decimal

Log Message:
-----------
Make the MONEY data type have a thousands separator != decimal symbol,
if the locale has the thousands separator as "". This now matches the
to_char and psql numericlocale behavior. (Previously this data type was
basically useless for such setups.)

Modified Files:
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pgsql/src/backend/utils/adt:
cash.c (r1.75 -> r1.76)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/cash.c?r1=1.75&r2=1.76)