(I64 only.) The Put Invocation Registers routine updates the
    fields of a given procedure invocation context.

    Note that if user override routines are specified in the
    invocation context block, then they are used to find and modify
    the invocation context.

    Format

      LIB$I64_PUT_INVO_REGISTERS   invo_handle, invo_context,

                                   [,gr_mask] [,fr_mask]

                                   [,br_mask] [,pr_mask] [,misc_mask]