multifd: Use normal pages array on the send side

multifd: Use normal pages array on the send side

We are only sending normal pages through multifd channels.
Later on this series, we are going to also send zero pages.
We are going to detect if a page is zero or non zero in the multifd
channel thread, not on the main thread.

So we receive an array of pages page->offset[N]

And we will end with:

p->normal[N - zero_pages]
p->zero[zero_pages].

In this patch, we just copy all the pages in offset to normal.

for (i = 0; i < pages->num; i++) {
    p->narmal[p->normal_num] = pages->offset[i];
    p->normal_num++:
}

Later in the series this becomes:

for (i = 0; i < pages->num; i++) {
    if (buffer_is_zero(page->offset[i])) {
        p->zerol[p->zero_num] = pages->offset[i];
        p->zero_num++:
    } else {
        p->narmal[p->normal_num] = pages->offset[i];
        p->normal_num++:
    }
}

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---

Improving comment (dave)
Renaming num_normal_pages to total_normal_pages (peter)