[perl #111646] Arity counting mis-treats slurpy and capture parameters

[Patrick R. Michaud via RT]

Now fixed in 69920db585.

    > say &infix:<~>.arity
    0
    > say &infix:<~>.count
    Inf
    > say <a b c d>.reduce(&infix:<~>)
    abcd

Ticket can be closed when we have appropriate spectests.

Thanks!

Pm