Factorization algorithms return `ReturnCode.Default` when it should be `ReturnCode.Success`

[vpuri3]

julia> prob = LinearProblem(rand(4, 4), rand(4)); sol = solve(prob, LUFactorization())
retcode: Default
u: 4-element Vector{Float64}:
  0.0561509562131119
  2.8927484238929284
 -2.005290617428258
 -1.0147124069649773

julia> prob.A * sol.u - prob.b
4-element Vector{Float64}:
  1.1102230246251565e-16
  1.1102230246251565e-16
 -2.220446049250313e-16
  0.0

[ChrisRackauckas]

Well it should check the retcode on the linear solver first, but yes it should report success if successful.