[libgit2-glib/wip/chergert/fix-build] submodule: fix invalid g_return_val_if_fail()

[Christian Hergert <chergert src gnome org>]

commit 10da7624b3b2d786b602037cec66e22ee4e7dc13
Author: Christian Hergert <chergert redhat com>
Date:   Mon Mar 4 16:23:38 2019 -0800

    submodule: fix invalid g_return_val_if_fail()
    
    This is breaking some builds that have strict compiler flags.

 libgit2-glib/ggit-submodule.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/libgit2-glib/ggit-submodule.c b/libgit2-glib/ggit-submodule.c
index 228d659..95e5428 100644
--- a/libgit2-glib/ggit-submodule.c
+++ b/libgit2-glib/ggit-submodule.c
@@ -439,7 +439,7 @@ ggit_submodule_update (GgitSubmodule               *submodule,
 
        g_return_if_fail (submodule != NULL);
        g_return_if_fail (submodule->valid);
-       g_return_val_if_fail (options == NULL || GGIT_IS_SUBMODULE_UPDATE_OPTIONS (options), NULL);
+       g_return_if_fail (options == NULL || GGIT_IS_SUBMODULE_UPDATE_OPTIONS (options));
        g_return_if_fail (error == NULL || *error == NULL);
 
        ret = git_submodule_update (submodule->submodule, init, options ? 
_ggit_submodule_update_options_get_submodule_update_options (options) : NULL);