exports: Never try to export /.flatpak-info

Just for completeness, in practice the host system will not have this.

Helps: https://github.com/flatpak/flatpak/issues/5205
Signed-off-by: Simon McVittie <smcv@collabora.com>

common/flatpak-exports.c

@@ -52,6 +52,7 @@
    flatpak_abs_usrmerged_dirs get the same treatment without having to be listed
    here. */
 const char *dont_export_in[] = {
+  "/.flatpak-info",
   "/app",
   "/dev",
   "/etc",