pull: fix GLNX_HASH_TABLE_FOREACH_KV regressions

These are regression from #971. We were stuffing a pointer size inside a
variable of integer size. So the assignment was spilling over into other
variables' storage space. Actually use a gpointer and GPOINTER_TO_[U]INT
as was done originally.

Also bump libglnx which has static checks for this error in the future.

Update submodule: libglnx

Closes: #990
Approved by: cgwalters

src/libostree/ostree-repo-checkout.c

@@ -1091,9 +1091,9 @@ ostree_repo_checkout_gc (OstreeRepo        *self,
   if (!to_clean_dirs)
     return TRUE; /* Note early return */
 
-  GLNX_HASH_TABLE_FOREACH (to_clean_dirs, guint, prefix)
+  GLNX_HASH_TABLE_FOREACH (to_clean_dirs, gpointer, prefix)
     {
-      g_autofree char *objdir_name = g_strdup_printf ("%02x", prefix);
+      g_autofree char *objdir_name = g_strdup_printf ("%02x", GPOINTER_TO_UINT (prefix));
       g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
 
       if (!glnx_dirfd_iterator_init_at (self->uncompressed_objects_dir_fd, objdir_name, FALSE,