Cmake is a build obfuscation mechanism.
I have never liked and I don't think I ever will. I've never seen
the benefit of this level of automation over the usual autoconf /
configure / make method. Every cmake package has different options;
there's no standardization and no sense. This case is particulary
nasty: there's no apparent way to make a 32bit compile short of
running it in a chroot. Every attempt fails at the library linking
stage: the 32-bit libraries are ignored as they are incompatible
with the 64-bit objects it should never have generated in the first
place. This is probably the last dependency before completing this
project by compiling wxgtk3-no-stl-gtk3-multilib, but it isn't
going to get done.