[vala] glib-2.0: Revert GLib.KeyFile.to_data change

[Jürg Billeter <juergbi src gnome org>]

commit 9df91c48bc036f41f7fbadf9f4f34017cccbe901
Author: Jürg Billeter <j bitron ch>
Date:   Mon Jun 1 10:22:03 2009 +0200

    glib-2.0: Revert GLib.KeyFile.to_data change
    
    g_key_file_to_data never throws an error. Revert earlier change and
    add explanation as comment.
---
 vapi/glib-2.0.vapi |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/vapi/glib-2.0.vapi b/vapi/glib-2.0.vapi
index 37c1d3e..f80fa5b 100644
--- a/vapi/glib-2.0.vapi
+++ b/vapi/glib-2.0.vapi
@@ -2739,7 +2739,8 @@ namespace GLib {
 		public bool load_from_dirs (string file, [CCode (array_length = false, array_null_terminated = true)] string[] search_dirs, out string full_path, KeyFileFlags @flags) throws KeyFileError;
 		public bool load_from_data (string data, ulong length, KeyFileFlags @flags) throws KeyFileError;
 		public bool load_from_data_dirs (string file, out string full_path, KeyFileFlags @flags) throws KeyFileError;
-		public string to_data (out size_t length = null) throws KeyFileError;
+		// g_key_file_to_data never throws an error according to the documentation
+		public string to_data (out size_t length = null, out GLib.Error error = null);
 		public string get_start_group ();
 		[CCode (array_length_type = "gsize")]
 		public string[] get_groups ();