`@ct_enable` incorrectly handles `Vararg`.

[MasonProtter]

Here's a MWE:

julia> @ct_enable function f(x::Vararg{Any, N}) where {N}
           N
       end
ERROR: TypeError: in TypeVar, in upper bound, expected Type, got Vararg{Any, N}
Stacktrace:
 [1] TypeVar(n::Symbol, ub::Any)
   @ Core ./boot.jl:254
 [2] top-level scope
   @ REPL[24]:1

and here's what's going wrong:

julia> @macroexpand1 @ct_enable function f(x::Vararg{Any, N}) where {N}
           N
       end
quote
    #= REPL[25]:1 =#
    function f(x::Vararg{Any, N}; ) where N
        (CompTime.comptime)(f, x)
    end
    #= REPL[25]:1 =#
    function CompTime.generate_code(::(typeof)(f), ::(Type){<:Vararg{Any, N}}; ) where N # <-------- This is bad
        $(Expr(:copyast, :($(QuoteNode(quote
    #= REPL[25]:1 =#
    #= REPL[25]:2 =#
    N
end)))))
    end
    #= REPL[25]:1 =#
    function CompTime.comptime(::(typeof)(f), x::Vararg{Any, N}; ) where N
        #= /home/mason/.julia/packages/CompTime/Ppb3B/src/CompTime.jl:137 =#
        if $(Expr(:generated))
            #= /home/mason/.julia/packages/CompTime/Ppb3B/src/CompTime.jl:138 =#
            (CompTime.generate_code)(f, Vararg{Any, N})
        else
            #= /home/mason/.julia/packages/CompTime/Ppb3B/src/CompTime.jl:140 =#
            $(Expr(:meta, :generated_only))
        end
    end
    #= REPL[25]:1 =#
    function CompTime.runtime(::(typeof)(f), x::Vararg{Any, N}; ) where N
        #= REPL[25]:1 =#
        #= REPL[25]:2 =#
        N
    end
end