Camellia on OS X?

Has anyone been able to build and use the Camellia library on OS X? I’ve
been trying for a few days to no avail. Scant resources and I am
admittedly not that knowledgeable.

The build dies on:
make: *** No rule to make target ruby.h', needed bycamellia_ruby_wrap.o’. Stop.

ruby.h definitely exists at:

Anyone have any experience installing Camellia on OS X?