[PATCH v3 2/6] tools/ocaml/xenstored: fix deprecation warning

[Edwin Török <edvin.torok@xxxxxxxxxx>]

```
File "xenstored/disk.ml", line 33, characters 9-23:
33 |    let c = Char.lowercase c in
              ^^^^^^^^^^^^^^
(alert deprecated): Stdlib.Char.lowercase
Use Char.lowercase_ascii instead.
```

Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
---
 tools/ocaml/xenstored/disk.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/ocaml/xenstored/disk.ml b/tools/ocaml/xenstored/disk.ml
index 4739967b61..1ca0e2a95e 100644
--- a/tools/ocaml/xenstored/disk.ml
+++ b/tools/ocaml/xenstored/disk.ml
@@ -30,7 +30,7 @@ let undec c =
        | _          -> raise (Failure "undecify")
 
 let unhex c =
-       let c = Char.lowercase c in
+       let c = Char.lowercase_ascii c in
        match c with
        | '0' .. '9' -> (Char.code c) - (Char.code '0')
        | 'a' .. 'f' -> (Char.code c) - (Char.code 'a') + 10
-- 
2.25.1