package managers wrapping dune must use release mode

Many dune packages have a makefile that contains targets such as dune build. While opam packages do the right thing and specify -p and a package name in order to enable release mode, I suspect that many other OS package managers do not do this and simply wrap the Makefile.

There are a few things that'll help:

• add a section to the dune docs on "Instructions for package managers" to explain the various dev/release profile options. There isn't a single one right now.
• consider adding a DUNE_PROFILE environment variable that a generic wrapper such as dh_ocaml in Debian can set to release in order to force release mode for the package.

If release mode is not set, then the resulting binaries from the package manager will have cross-module inlining disabled.

Start with the Dune documentation and the Makefile targets that invoke dune build, then trace how package-manager wrappers choose dev or release profiles. Done means documenting the profile options and defining how a wrapper such as Debian's dh_ocaml can select release mode through DUNE_PROFILE.