emacsWithPackages: support installing larger packages

[rvl]

Motivation for this change

I was getting the following error building tide from Melpa:

nix-build  -E '(import <nixpkgs> {}).emacs25WithPackages (p: [p.melpaPackages.tide])'

File tide-20170509.1134.tar is large (10.2M), really open? (y or n) Error reading from stdin
builder for ‘/nix/store/gs9ik7yf8iilsikkfing74i70m0diax3-emacs-tide-20170509.1134.drv’ failed with exit code 255
cannot build derivation ‘/nix/store/m3p080aani4rw82llp8nqk93cw2nvirk-emacs-with-packages-25.2.drv’: 1 dependencies couldn't be built

Solution was to disable the large file warning threshold when installing packages.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

[mdorman]

I'm a bit startled to find there's a 10MB package, but given that that's the case, it seems sensible to me.

[grahamc]

Thank you!

[rvl]

Thanks @mdorman @grahamc