[dune] Move to Dune 1.10, use coq.pp directive.

We use the `(coq.pp ...)` dune directive which will produce correct
error messages for `.mlg` files.

Unfortunately we cannot yet use the automatic opam generation features
of Dune 1.10, as this does require a fully native Dune build.

Dune 1.6-1.10 has quite a few other improvements that could be used by
Coq, for example for promote modes.

I have fixed a couple of documentation issues. `Drop` and `ocamldebug`
have been tested in this version.

1 files changed, 1 insertions, 1 deletions

diff --git a/coq.opam b/coq.opam
index 05b20e08b6..585e9df789 100644
--- a/coq.opam
+++ b/coq.opam
@@ -20,7 +20,7 @@ license: "LGPL-2.1"
 
 depends: [
   "ocaml"     {         >= "4.05.0" }
-  "dune"      { build & >= "1.6.0"  }
+  "dune"      { build & >= "1.10.0"  }
   "ocamlfind" { build }
   "num"
 ]