Limit a multivalued param that is followed by another required param

Limit a multivalued param that is followed by another required param

A multivalued parameter that is followed by another required parameter is
limited to a single value unless prefaced with its switch, eg:

	pts adduser A B C D

B, C and D are group names and A is a user name, despite the user name field
taking multiple values.  In contrast in:

	pts adduser -user A B -group C D

A and B are users and only C and D are groups.

Signed-off-by: David Howells <dhowells@redhat.com>