migration: Create ram_save_multifd_page

The function still don't use multifd, but we have simplified
ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
counter.

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

--
Add last_page parameter
Add commets for done and address
Remove multifd field, it is the same than normal pages
Merge next patch, now we send multiple pages at a time
Remove counter for multifd pages, it is identical to normal pages
Use iovec's instead of creating the equivalent.
Clear memory used by pages (dave)
Use g_new0(danp)
define MULTIFD_CONTINUE
now pages member is a pointer
Fix off-by-one in number of pages in one packet
Remove RAM_SAVE_FLAG_MULTIFD_PAGE
s/multifd_pages_t/MultiFDPages_t/
add comment explaining what it means
diff --git a/migration/migration.c b/migration/migration.c
index 2680ba2..d075c27 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2708,7 +2708,7 @@
 /* How many bytes have we transferred since the beggining of the migration */
 static uint64_t migration_total_bytes(MigrationState *s)
 {
-    return qemu_ftell(s->to_dst_file);
+    return qemu_ftell(s->to_dst_file) + ram_counters.multifd_bytes;
 }
 
 static void migration_calculate_complete(MigrationState *s)