rnd: break out prng from xutils

We only need it in curvetun, this makes it easier to maintain.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
xio: refactor fopencookie related functions

Again, we move them out of xio to shrink it down.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
xio: add ioexact operations

Break this out so that we only need to have sigint non-static where
it is really needed.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
xio: rename xio to ioops and reduce its includes

Rename xio to ioops (io-ops) and boil its include files down to a
minimum.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>