dirtree.c: avoid spurious EINVAL warnings.

An Android engineer complained that they were seeing this when not
running as root:

  $ adb shell ls
  ls: ./postinstall: Invalid argument
  ls: ./init: Permission denied
  ls: ./data_mirror: Invalid argument
  ls: ./init.environ.rc: Invalid argument
  ls: ./metadata: Invalid argument
  acct
  adb_keys
  apex

From strace, it was here:

  newfstatat(4, "adb_keys", 0x7fc67eca88, AT_SYMLINK_NOFOLLOW) = -1 EACCES (Permission denied)
  readlinkat(4, "adb_keys", 0x5e843c7720, 4095) = -1 EINVAL (Invalid argument)

So stop looking at st.st_mode (and then deciding to do a readlinkat())
if we didn't actually successfully stat().

0 files changed, 0 insertions, 0 deletions