R: Add enableShared/enableStatic arguments

[nh2]

Motivation for this change

Building libR.a for static linking.

Care was taken to not modify the derivation to trigger mass rebuilds with the default arguments.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @peti @timokau

[nh2]

@GrahamcOfBorg eval R

[peti]

Just out of curiosity: why would you want to link R packages statically?

[nh2]

Just out of curiosity: why would you want to link R packages statically?

Linking the R interpreter library statically would allow to create single binaries that can interpret R scripts. My own end goal for that is to be able to link the Haskell packages inline-r and H statically for static-haskell-nix.

[nh2]

@GrahamcOfBorg build R

[nh2]

@peti Points addressed, please have another look :)