migration: set error if select return one error

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

migration.c

diff --git a/migration.c b/migration.c
index 260e5b5..a682168 100644
--- a/migration.c
+++ b/migration.c
@@ -453,6 +453,10 @@
 
         ret = select(s->fd + 1, NULL, &wfds, NULL, NULL);
     } while (ret == -1 && (s->get_error(s)) == EINTR);
+
+    if (ret == -1) {
+        qemu_file_set_error(s->file);
+    }
 }
 
 int migrate_fd_close(void *opaque)