_GLNX_TEST_SCOPED_TEMP_DIR: Fix memory and fd leak

This doesn't really matter, since it only happens when our process is
about to exit anyway, but it makes it easier to use AddressSanitizer
and similar tools.

Signed-off-by: Simon McVittie <smcv@collabora.com>

tests/libglnx-testlib.c

@@ -23,6 +23,8 @@
 
 #include <errno.h>
 
+#include <glib/gstdio.h>
+
 #include "libglnx.h"
 
 struct _GLnxTestAutoTempDir
@@ -63,4 +65,10 @@ _glnx_test_auto_temp_dir_leave (_GLnxTestAutoTempDir *dir)
 
   glnx_tmpdir_delete (&dir->temp_dir, NULL, &error);
   g_assert_no_error (error);
+
+  g_close (dir->old_cwd_fd, &error);
+  g_assert_no_error (error);
+
+  g_free (dir->old_cwd);
+  g_free (dir);
 }