Fix build with lablgtk 2.16.
Apply conditionally because it uses new types introduced in this version.


Index: coq-8.3pl4/ide/preferences.ml
===================================================================
--- coq-8.3pl4.orig/ide/preferences.ml
+++ coq-8.3pl4/ide/preferences.ml
@@ -31,6 +31,10 @@ let mod_to_str (m:Gdk.Tags.modifier) =
     | `CONTROL -> "CONTROL"
     | `LOCK -> "LOCK"
     | `SHIFT -> "SHIFT"
+    | `HYPER -> "HYPER"
+    | `META -> "META"
+    | `RELEASE -> "RELEASE"
+    | `SUPER -> "SUPER"
 
 let (str_to_mod:string -> Gdk.Tags.modifier) =
   function
@@ -47,6 +51,10 @@ let (str_to_mod:string -> Gdk.Tags.modif
     | "CONTROL" -> `CONTROL
     | "LOCK" -> `LOCK
     | "SHIFT" -> `SHIFT
+    | "HYPER" -> `HYPER
+    | "META" -> `META
+    | "RELEASE" -> `RELEASE
+    | "SUPER" -> `SUPER
     | s -> `MOD1
 
 type pref =
Index: coq-8.3pl4/ide/utils/okey.ml
===================================================================
--- coq-8.3pl4.orig/ide/utils/okey.ml
+++ coq-8.3pl4/ide/utils/okey.ml
@@ -47,6 +47,10 @@ let int_of_modifier = function
   | `BUTTON3 -> 1024
   | `BUTTON4 -> 2048
   | `BUTTON5 -> 4096
+  | `HYPER -> 8192
+  | `META -> 16384
+  | `RELEASE -> 32768
+  | `SUPER -> 65536
 
 let print_modifier l =
   List.iter