Given an ip_value, find the address of the unwind information
    block language specific data area (LSDA), and write it to
    unwind_lsda_p. If not present, then write 0 to unwind_lsda_p.

    Format
      LIB$X86_GET_UNWIND_LSDA (ip_value, unwind_lsda_p)

1  –  Returns

 status

    A value of 1 indicates success. A value of 0 indicates failure.

2  –  Arguments

 ip_value

    OpenVMS usage: IP value
    type:          quadword
    access:        read
    mechanism:     by reference

    Address of a location that contains the IP value. ip_value is
    used to find the unwind information and language-specific data
    area address.

 unwind_lsda_p

    OpenVMS usage: address
    type:          quadword
    access:        write
    mechanism:     by reference

    Address of a quadword to receive the address of the language-
    specific data area, if there is one.