[perl-Glib-Object-Introspection] Allow undef for callback user data

[Torsten Schönfeld <tsch src gnome org>]

commit e147134ee65237c8209cd9eca7d8800df75ad445
Author: Torsten Schönfeld <kaffeetisch gmx de>
Date:   Mon May 23 23:23:27 2011 +0200

    Allow undef for callback user data

 GObjectIntrospection.xs |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/GObjectIntrospection.xs b/GObjectIntrospection.xs
index 2e79cbc..b72b8f0 100644
--- a/GObjectIntrospection.xs
+++ b/GObjectIntrospection.xs
@@ -1219,8 +1219,10 @@ sv_to_arg (SV * sv,
         memset (arg, 0, sizeof (GIArgument));
 
 	if (!gperl_sv_is_defined (sv))
-		/* Interfaces need to be able to handle undef separately. */
-		if (!may_be_null && tag != GI_TYPE_TAG_INTERFACE)
+		/* Interfaces and void types need to be able to handle undef
+		 * separately. */
+		if (!may_be_null && tag != GI_TYPE_TAG_INTERFACE
+		                 && tag != GI_TYPE_TAG_VOID)
 			ccroak ("undefined value for mandatory argument '%s' encountered",
 			       g_base_info_get_name ((GIBaseInfo *) arg_info));