Byte swapping and bindat

[Po Lu]

I was looking into replacing some of the very complicated Motif binary
message parsing code in x-dnd.el with bindat, but there doesn't seem to
be a way to make bindat do byte-swapping automatically, which makes it a
lot less attractive.

Is there a way to specify a bindat type with fields whose endianess
depends on an external parameter (or another field of the type?)

Defining each type twice for both byte orders seems very ugly.