Currently, vmstate.h includes helper macro variants for 8, 16 and 32-bit
unsigned integers which include a "test" function which can selectively
enable or disable the field's presence in the migration stream.

There aren't similar helpers for 64-bit unsigned integers, or any size of
signed integers.  This patch remedies this.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>