longdef1 strips lines

[cstjean]

longdef1 gets rid of line numbers:

julia> fun = :(f(x) = x+2)
:(f(x) = begin
          #= REPL[37]:1 =#
          x + 2
      end)

julia> MacroTools.longdef1(fun)
:(function f(x)
      x + 2
  end)

And since it's relied upon by splitdef, we lose line numbers there too.