stubs: group stubs for user-mode emulation

Some stubs are used for user-mode emulation only; they are not
needed by tools.  Move them out of stubs/.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

stubs/replay-user.c

@@ -1,33 +0,0 @@
-/*
- * replay.c
- *
- * Copyright (c) 2010-2015 Institute for System Programming
- *                         of the Russian Academy of Sciences.
- *
- * This work is licensed under the terms of the GNU GPL, version 2 or later.
- * See the COPYING file in the top-level directory.
- *
- */
-
-#include "qemu/osdep.h"
-#include "sysemu/replay.h"
-
-bool replay_exception(void)
-{
-    return true;
-}
-
-bool replay_has_exception(void)
-{
-    return false;
-}
-
-bool replay_interrupt(void)
-{
-    return true;
-}
-
-bool replay_has_interrupt(void)
-{
-    return false;
-}