sdbus++: generate signal broadcast bindings

Change-Id: If1b04fedc95614c95a23768f95801e2bb9b4c0e9
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/tools/templates/interface.mako.server.cpp b/tools/templates/interface.mako.server.cpp
index 63bc788..63374db 100644
--- a/tools/templates/interface.mako.server.cpp
+++ b/tools/templates/interface.mako.server.cpp
@@ -23,11 +23,18 @@
 ${ m.cpp_prototype(loader, interface=interface, ptype='callback-cpp') }
     % endfor
 
+    % for s in interface.signals:
+${ s.cpp_prototype(loader, interface=interface, ptype='callback-cpp') }
+    % endfor
+
 const vtable::vtable_t ${classname}::_vtable[] = {
     vtable::start(),
     % for m in interface.methods:
 ${ m.cpp_prototype(loader, interface=interface, ptype='vtable') }
     % endfor
+    % for s in interface.signals:
+${ s.cpp_prototype(loader, interface=interface, ptype='vtable') }
+    % endfor
     vtable::end()
 };