coqPackages.coquelicot: 2.1.1 -> 2.1.2

keeping old 2.1.1 version for Coq-8.4,
as newer versions of the library do not support older Coq versions

pkgs/development/coq-modules/coquelicot/default.nix

@@ -1,11 +1,26 @@
 { stdenv, fetchurl, which, coq, ssreflect }:
 
-stdenv.mkDerivation {
-  name = "coq${coq.coq-version}-coquelicot-2.1.1";
-  src = fetchurl {
+let param =
+  let
+  v2_1_1 = {
+    version = "2.1.1";
     url = https://gforge.inria.fr/frs/download.php/file/35429/coquelicot-2.1.1.tar.gz;
     sha256 = "1wxds73h26q03r2xiw8shplh97rsbim2i2s0r7af0fa490bp44km";
   };
+  v2_1_2 = {
+    version = "2.1.2";
+    url = https://gforge.inria.fr/frs/download.php/file/36320/coquelicot-2.1.2.tar.gz;
+    sha256 = "09q9xbzyndx8i68hn3ir4pmzgqd1q33qpk3xghf2l849g8w3q5an";
+  };
+  in {
+  "8.4" = v2_1_1;
+  "8.5" = v2_1_2;
+  "8.6" = v2_1_2;
+}."${coq.coq-version}"; in
+
+stdenv.mkDerivation {
+  name = "coq${coq.coq-version}-coquelicot-${param.version}";
+  src = fetchurl { inherit (param) url sha256; };
 
   nativeBuildInputs = [ which ];
   buildInputs = [ coq ];