Skip unlinked mountpoints (broken network fs endpoints)

Change-Id: I49baac7e65584d391f8de99fa90ddcbb1aeb6bba
diff --git a/_modules/auditd.py b/_modules/auditd.py
index d5445a8..f2b6a84 100644
--- a/_modules/auditd.py
+++ b/_modules/auditd.py
@@ -39,6 +39,8 @@
             fpath = os.path.join(root, fname)
             if os.path.islink(fpath):
                 continue
+            if not os.path.exists(fpath):
+                continue
             mode = os.stat(fpath).st_mode
             if (mode & e_bits) and (mode & s_bits):
                 yield fpath