aufs standalone: cosmetic, missing copyright sentence

commit 325d277142a1fff5ac844886d2495cfee5c1e7d0 aufs5-standalone upstream.

I just forgot merging the copyright sentences in the new source file
fs/aufs/fsctx.c.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>