Use the new, better (and incompatible) ADT.struct

Rev: lib/modules/ADT.pmod/struct.pike:1.5
Rev: lib/modules/Protocols.pmod/X.pmod/Auth.pmod:1.4
Rev: lib/modules/Protocols.pmod/X.pmod/Xlib.pmod:1.33
Rev: lib/modules/Protocols.pmod/X.pmod/my_struct.pmod:1.7
Rev: lib/modules/SSL.pmod/handshake.pike:1.7
Rev: lib/modules/Standards.pmod/ASN1.pmod/decode.pike:1.2