tomoyo: Fix pathname calculation breakage.

Commit 7177a9c4

 ("fs: call rename2 if exists") changed
"struct inode_operations"->rename == NULL if
"struct inode_operations"->rename2 != NULL .

TOMOYO needs to check for both ->rename and ->rename2 , or
a system on (e.g.) ext4 filesystem won't boot.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>