sdbus++: Fix mako include substitution for signals

This allows the signal generator to emit include directives

Change-Id: I47a13102491116772c31b57ca58824fda3612938
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/tools/sdbusplus/templates/interface.mako.server.cpp.in b/tools/sdbusplus/templates/interface.mako.server.cpp.in
index 0043f75..a47ff38 100644
--- a/tools/sdbusplus/templates/interface.mako.server.cpp.in
+++ b/tools/sdbusplus/templates/interface.mako.server.cpp.in
@@ -3,12 +3,9 @@
 #include <sdbusplus/server.hpp>
 #include <sdbusplus/exception.hpp>
 #include <${"/".join(interface.name.split('.') + [ 'server.hpp' ])}>
-% for m in interface.methods:
+% for m in interface.methods + interface.properties + interface.signals:
 ${ m.cpp_prototype(loader, interface=interface, ptype='callback-cpp-includes') }
 % endfor
-% for p in interface.properties:
-${ p.cpp_prototype(loader, interface=interface, ptype='callback-cpp-includes') }
-% endfor
 <%
     namespaces = interface.name.split('.')
     classname = namespaces.pop()