[glib] Fix indicative gschema.dtd regarding range.

[Arnaud B. <arnaudb src gnome org>]

commit 438547641f5d9c65f07254b0948b269e45891ef4
Author: Arnaud B <arnaud bonatti gmail com>
Date:   Mon Aug 13 08:19:57 2018 +0000

    Fix indicative gschema.dtd regarding range.
    
    The range can have only a "min" or only a "max" attribute, and can even have no attributes at all.

 gio/gschema.dtd | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gio/gschema.dtd b/gio/gschema.dtd
index 8cd552d4a..1599f8de7 100644
--- a/gio/gschema.dtd
+++ b/gio/gschema.dtd
@@ -49,8 +49,8 @@
 <!ELEMENT range EMPTY >
 <!-- min and max must be parseable as values of the key type and
      min must be less than or equal to max -->
-<!ATTLIST range min CDATA #REQUIRED
-                max CDATA #REQUIRED >
+<!ATTLIST range min CDATA #IMPLIED
+                max CDATA #IMPLIED >
 
 <!-- choices is only allowed for keys with string or string array type -->
 <!ELEMENT choices (choice+) >