pgsql: Add possibility to generate only some files, by passing

Log Message:
-----------
Add possibility to generate only some files, by passing command-line
arguments.

Modified Files:
--------------
pgsql/src/backend/utils/mb/Unicode:
UCS_to_most.pl (r1.5 -> r1.6)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/mb/Unicode/UCS_to_most.pl?r1=1.5&r2=1.6)