Fix build with new yank feature by adding stubs

Fixes: 50186051f4 ("Introduce yank feature")
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
[AJB: tweak MAINTAINERS]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210114141918.5201cc9c@gecko.fritz.box>
Message-Id: <20210114165730.31607-11-alex.bennee@linaro.org>

MAINTAINERS

@@ -2736,6 +2736,7 @@ Yank feature
 M: Lukas Straub <lukasstraub2@web.de>
 S: Odd fixes
 F: util/yank.c
+F: stubs/yank.c
 F: include/qemu/yank.h
 F: qapi/yank.json
 

stubs/meson.build

@@ -47,6 +47,7 @@ stub_ss.add(files('vm-stop.c'))
 stub_ss.add(files('win32-kbd-hook.c'))
 stub_ss.add(files('cpu-synchronize-state.c'))
 if have_block
+  stub_ss.add(files('yank.c'))
   stub_ss.add(files('replay-tools.c'))
 endif
 if have_system

stubs/yank.c

@@ -0,0 +1,29 @@
+#include "qemu/osdep.h"
+#include "qemu/yank.h"
+
+bool yank_register_instance(const YankInstance *instance, Error **errp)
+{
+    return true;
+}
+
+void yank_unregister_instance(const YankInstance *instance)
+{
+}
+
+void yank_register_function(const YankInstance *instance,
+                            YankFn *func,
+                            void *opaque)
+{
+}
+
+void yank_unregister_function(const YankInstance *instance,
+                              YankFn *func,
+                              void *opaque)
+{
+}
+
+void yank_generic_iochannel(void *opaque)
+{
+}
+
+