compat-ioctl.c: fix compile with no CONFIG_JBD

The ext3 compat-ioctl translation wants to translate data structures
that <linux/jbd.h> only declared when CONFIG_JBD was enabled.

So make <linux/jbd.h> play nicely even when we don't actually end up
using it.

Acked-by: Andrew Morton <akpm@osdl.org>
Acked-by: Jeffrey Hundstad <jeffrey.hundstad@mnsu.edu>
Acked-by: Zan Lynx <zlynx@acm.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>