migration: Split vmstate-types.c from vmstate.c

Now one just has the interperter, and the other has the basic types.
Once there, add copyright boilerplate.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>

--

Use GPL v2 or later.  Detected by David.

migration/Makefile.objs

@@ -1,7 +1,7 @@
 common-obj-y += migration.o socket.o fd.o exec.o
 common-obj-y += tls.o channel.o
 common-obj-y += colo-comm.o colo.o colo-failover.o
-common-obj-y += vmstate.o page_cache.o
+common-obj-y += vmstate.o vmstate-types.o page_cache.o
 common-obj-y += qemu-file.o
 common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o