Only set permissions on dirs or files

Traversal would mark directories with the correct permissions, but
they're visited again in post-order which is a different fts_info flag.
Then it would set that to regular file permissions.

Explicitly check to make sure we're looking at a file instead.

Bug: 6478606
Change-Id: I13cab3e69f451da6a994fa974d575ef366f82025

VolumeManager.cpp

@@ -571,7 +571,7 @@ int VolumeManager::fixupAsecPermissions(const char *id, gid_t gid, const char* f
 
             if (ftsent->fts_info & FTS_D) {
                 result |= fchmod(fd, 0711);
-            } else {
+            } else if (ftsent->fts_info & FTS_F) {
                 result |= fchmod(fd, privateFile ? 0640 : 0644);
             }
             close(fd);