https://bugzilla.redhat.com/show_bug.cgi?id=1569678

On some large systems (with ~400GB of RAM) it is possible for
unsigned int to overflow in which case we report invalid number
of 4K pages pool size. Switch to unsigned long long.

We hit overflow in virNumaGetPages when doing:

    huge_page_sum += 1024 * page_size * page_avail;

because although 'huge_page_sum' is an unsigned long long, the
page_size and page_avail are both unsigned int, so the promotion
to unsigned long long doesn't happen until the sum has been
calculated, by which time we've already overflowed.

Turning page_avail into a unsigned long long is not strictly
needed until we need ability to represent more than 2^32
4k pages, which equates to 16 TB of RAM. That's not
outside the realm of possibility, so makes sense that we
change it to unsigned long long to avoid future problems.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>