CRAN macOS Deployment

Considerations of additional tools and libraries that are required for some packages outside of the recipes setup.

• zlib.pc - some .pcs (at least cairo and libpng) require configuration files for existing system libraries such as libz or else pkg-config will fail. We are currently using https://mac.r-project.org/libs-4/pkgconfig-system-stubs-darwin13.tar.gz Maybe we should create a recipe that synthesizes this?

• JAGS - https://sourceforge.net/projects/mcmc-jags/files/JAGS/4.x/Mac%20OS%20X/

• iODBC - requires headers from https://opensource.apple.com/tarballs/iodbc/iodbc-42.6.tar.gz - libraries are already present in the system. There are two sets - the ones in mac have an extra iODBC prefix but packages like RODBC don't work with them unless they are sym-linked one level down like the regular ones.