Fix building P2P code against old glib versions

When building the OstreeBloom code against old versions of glib, we have
to have the libglnx headers included so that it defines
G_DEFINE_AUTOPTR_CLEANUP_FUNC and friends for us.

This is similarly true for test-repo-finder-mount.c which indirectly
includes ostree-autocleanups.h.

Closes: #1605
Approved by: cgwalters

src/libostree/ostree-bloom-private.h

@@ -28,6 +28,8 @@
 #include <glib.h>
 #include <glib-object.h>
 
+#include "libglnx.h"
+
 G_BEGIN_DECLS
 
 /**

tests/test-repo-finder-mount.c

@@ -27,6 +27,7 @@
 #include <gio/gio.h>
 #include <glib.h>
 #include <glib-object.h>
+#include <libglnx.h>
 #include <locale.h>
 
 #include "libostreetest.h"