Fix listing of Android root directory when it is accessible

Fix listing of Android root directory when it is accessible

* src/androidvfs.c (android_root_closedir, android_root_dirfd)
(android_root_opendir): Allocate an ersatz file descriptor even
if directory is non-NULL, so that at-funcs will properly return
file status for virtual files in the root directory.

(cherry picked from commit 0cf9b58228580bfa400cdaf35eac04d375fe4785)