merge compat_ioctl.h into compat_ioctl.c

Now that there is no arch-specific compat ioctl handling left there is not
point in having a separate copat_ioctl.h, so merge it into compat_ioctl.c

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>