sdbus++: Allow server.hpp files to have extra generated includes

This allows for a future change that adds includes to the generated
server.hpp file that it needs for enum definitions.

Change-Id: Id8ecd03a8cc1155cc9032840f38bf5ccb28d40c0
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/tools/sdbusplus/templates/interface.mako.server.hpp b/tools/sdbusplus/templates/interface.mako.server.hpp
index 0774fe5..93cf6e7 100644
--- a/tools/sdbusplus/templates/interface.mako.server.hpp
+++ b/tools/sdbusplus/templates/interface.mako.server.hpp
@@ -3,6 +3,9 @@
 #include <systemd/sd-bus.h>
 #include <sdbusplus/sdbus.hpp>
 #include <sdbusplus/server.hpp>
+% for m in interface.methods + interface.properties + interface.signals:
+${ m.cpp_prototype(loader, interface=interface, ptype='callback-hpp-includes') }
+% endfor
 <%
     namespaces = interface.name.split('.')
     classname = namespaces.pop()