mumps3_struct.jl patch for MUMPS 5.9.0

[jose-rascon]

As per MUMPS 5.9.0 the [sdcz]mumps_c.h file has an additional argument called nb_singular_values which is 4 bytes long.

This caused that, upon calculating the Schur complement (with ICNTL(19)=3) one would obtain SIZE_SCHUR=0.

To fix this, between the lines 102-109 in mumps3_struc.jl, which previously read:

    deficiency::MUMPS_INT
    pivnul_list::Ptr{MUMPS_INT}
    mapping::Ptr{MUMPS_INT}
    singular_values::Ptr{TR}

    size_schur::MUMPS_INT
    listvar_schur::Ptr{MUMPS_INT}
    schur::Ptr{TC}

one has to include nb_singular_values::MUMPS_INT such that:

    deficiency::MUMPS_INT
    pivnul_list::Ptr{MUMPS_INT}
    mapping::Ptr{MUMPS_INT}
    singular_values::Ptr{TR}
    nb_singular_values::MUMPS_INT

    size_schur::MUMPS_INT
    listvar_schur::Ptr{MUMPS_INT}
    schur::Ptr{TC}