changed prs_unistr to parse empty and non-empty strings the same way.

changed prs_unistr to parse empty and non-empty strings the same way.
fixed typo in SPOOLSS_SYNT
some cleanup of unused functions
wrote make_spoolss_enumprinter and make_spoolss_openprinterex for
rpcclient as I'm trying to keep in sync the parsing code between HEAD and
TNG.

Will commit changes to TNG after lunch.

	J.F.
(This used to be commit 025cdb345f6de287a41d4449b2662dbc5e762bf2)