Add custom deserialize method for UmfpackLU to avoid memory leak

[andreasnoack]

Fixes JuliaLang/LinearAlgebra.jl#317

I'm not sure what would be a good way to test this. Can I compare some of the values from the GC output before and after running

foreach(1:10000) do i
    seekstart(b)
    serialize(b, F)
    seekstart(b)
    SuiteSparse.UMFPACK.umfpack_symbolic!(deserialize(b))
end

Which of the gc values would be appropriate to compare?

[ViralBShah]

Do we have to do it for all the factorizations in SuiteSparse?

[fredrikekre]

You will have to add Serialization to SuiteSparse/Project.toml as a dependency.