[R-SIG-Mac] building 32-bit version of R 3.x

[Alexy Khrabrov]

> They are both installed into the same "fat" framework. Everything is shared (i.e. files exist only once) except for the .so objects and some configurations that are in separate subdirectories based on the r_arch setting. OS X supports multiple architectures in one binary, that's why you don't need to modify any paths. OS X was running several architectures in parallel for a long time (first PPC+Intel then ppc+ppc64+i386+x86_64) so it "just works". The only thing to remember is that when you are compiling 3rd party dependencies, you must compile them "fat" for both architectures as well (or use lipo to combine them).

Great -- so how should I configure R build to do that?  Obviously the
above builds only one.

A+