Unused parameter in vacuum.c

Hi,

When I was reading vacuum.c, I found that the parameter 'stmttype' of
get_rel_oids() is not used at all.  The parameter had been used as
command tag in the notice message about "invalid object type", but now
such messages are reported by other functions.

Please find attached remove-unused-parameter patch.

Regards,
--
Shigeru Hanada