tree-wide: Fix the build with old glib (Ubuntu Trusty etc.)

This regressed with <https://github.com/ostreedev/ostree/pull/1040>
but currently the Travis builds aren't gating.

Closes: #1051
Approved by: jlebon

src/libostree/ostree-deployment.c

@@ -20,9 +20,9 @@
 
 #include "config.h"
 
+#include "otutil.h"
 #include "ostree.h"
 #include "ostree-deployment-private.h"
-#include "libglnx.h"
 
 typedef GObjectClass OstreeDeploymentClass;