clip_diag -- Cut out main diagonal

    call a%clip_diag(b,info)

Returns a copy of a without the main diagonal.

Type:: Asynchronous.
On Entry
a: the sparse matrix.
A variable of type psb_Tspmat_type.
Scope: local.

On Return
b: A copy of a without the main diagonal.
A variable of type psb_Tspmat_type.
info: Return code.