hw/core: Move system emulation files to system_ss

hotplug.c, qdev-hotplug.c and reset.c are not used by user emulation
and need not be included in hwcore_ss.  Move them to system_ss, where
they belong, by letting the linker pull in the stubs when needed.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240408155330.522792-8-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

stubs/hotplug-stubs.c

@@ -0,0 +1,34 @@
+/*
+ * Hotplug handler stubs
+ *
+ * Copyright (c) Red Hat
+ *
+ * Authors:
+ *  Philippe Mathieu-Daudé <philmd@redhat.com>,
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * 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 "hw/qdev-core.h"
+
+HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
+{
+    return NULL;
+}
+
+void hotplug_handler_pre_plug(HotplugHandler *plug_handler,
+                              DeviceState *plugged_dev,
+                              Error **errp)
+{
+    g_assert_not_reached();
+}
+
+void hotplug_handler_plug(HotplugHandler *plug_handler,
+                          DeviceState *plugged_dev,
+                          Error **errp)
+{
+    g_assert_not_reached();
+}

stubs/meson.build

@@ -14,6 +14,7 @@ stub_ss.add(files('fdset.c'))
 stub_ss.add(files('gdbstub.c'))
 stub_ss.add(files('get-vm-name.c'))
 stub_ss.add(files('graph-lock.c'))
+stub_ss.add(files('hotplug-stubs.c'))
 if linux_io_uring.found()
   stub_ss.add(files('io_uring.c'))
 endif