Like a few other drivers the vc driver is doing unlocked careless
references to file offsets.  Its got kind of 2.2 locking that hasnt been
updated in the lseek function so someone at least tried. 

Fortunately we have a real lock for this and can just make lseek use that
too.

The 'assume 64bit load is atomic' bug seems to be very widely spread

akpm@osdl.org:

   Move declarations to vt_kern.h
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>