[vala] codegen: Include gio/gio.h for "use_string_marshalling"

[Rico Tzschichholz <ricotz src gnome org>]

commit ed3d936aaf368705c9d2a504797a110b2f03abec
Author: Jordan Yelloz <jordan yelloz me>
Date:   Fri Jul 8 11:41:35 2016 -0700

    codegen: Include gio/gio.h for "use_string_marshalling"
    
    Using [DBus (use_string_marshalling = true)] requires G_DBUS_ERROR symbols
    and therefore needs gio/gio.h while e.g. defining enum in dedicated file.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768588

 codegen/valagvariantmodule.vala |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/codegen/valagvariantmodule.vala b/codegen/valagvariantmodule.vala
index 409940e..b2d9861 100644
--- a/codegen/valagvariantmodule.vala
+++ b/codegen/valagvariantmodule.vala
@@ -149,6 +149,9 @@ public class Vala.GVariantModule : GAsyncModule {
                        // strcmp
                        cfile.add_include ("string.h");
 
+                       // for G_DBUS_ERROR
+                       cfile.add_include ("gio/gio.h");
+
                        cfile.add_function (generate_enum_from_string_function (en));
                        cfile.add_function (generate_enum_to_string_function (en));
                }