headers: types.h -- Move BITS_PER_LONG to own header

This diet types.h and allows to include BITS_PER_LONG
only where really needed. It makes BITS_PER_LONG definition
close to one used in kernel.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>