migrate response file support to process directly?

[gbaz]

Given that lots of programs now support response files, and that we're teaching haskell tools one-by-one to support response files, do we want to put support for calling programs with response files into the process library directly? I'd suggest a new external lib, but the things we want to provide this to are all rather low in the dep-tree themselves -- i.e., ghc itself, cabal, hsc2hs, etc.

I'd think we could just e.g. port over http://hackage.haskell.org/package/Cabal-2.4.1.0/docs/Distribution-Simple-Program-ResponseFile.html

[hvr]

Note that we wouldn't be able to use this neither in tools such as Cabal nor in hsc2hs any time soon as we wouldn't want to impose a tight lower bound on process. So this would be something for the long-term future.

[snoyberg]

Nice idea. I have no problem with such a change, and don't have much opinion on the bike shed color. @gbaz were you interested in sending a PR yourself, or just kicking off the conversation here?