conf-autoconf hard dependency

[jonahbeckford]

conf-autoconf is included as a dependency in https://github.com/ocaml/opam-repository/blob/86961ac6d7505a361cd605968329990033691c57/packages/stdcompat/stdcompat.19/opam#L13

It isn't needed; I can compile stdcompat without it because configure and Makefile.in are checked into the code. Can this be an optional (depopts) dependency so we don't have to complicate the install for native Windows users? An alternative is a stdcompat-dev.opam package just for edits of the source code (like autoconf).

For now I'll remove the conf-autoconf dependency as a patch in the DkML repository.

[jonahbeckford]

Here is the patch I did: https://github.com/diskuv/diskuv-opam-repository/blob/0a78353ea36f2c8cc6bc0bfe12ce4327695d7bc8/packages/stdcompat/stdcompat.19%2Boptautoconf/opam#L15-L16