add explicit dependencies on services.h

SConscript

@@ -32,7 +32,7 @@ env.Library('cereal', cereal_objects)
 env.SharedLibrary('cereal_shared', cereal_objects)
 
 cereal_dir = Dir('.')
-env.Command(
+services_h = env.Command(
   ['services.h'],
   ['service_list.yaml', 'services.py'],
   'python3 ' + cereal_dir.path + '/services.py > $TARGET')
@@ -45,13 +45,15 @@ messaging_objects = env.SharedObject([
 ])
 
 messaging_lib = env.Library('messaging', messaging_objects)
+Depends('messaging/impl_zmq.cc', services_h)
 
 # note, this rebuilds the deps shared, zmq is statically linked to make APK happy
 # TODO: get APK to load system zmq to remove the static link
 shared_lib_shared_lib = [zmq, 'm', 'stdc++'] + ["gnustl_shared"] if arch == "aarch64" else []
 env.SharedLibrary('messaging_shared', messaging_objects, LIBS=shared_lib_shared_lib)
 
 env.Program('messaging/bridge', ['messaging/bridge.cc'], LIBS=[messaging_lib, 'zmq'])
+Depends('messaging/bridge.cc', services_h)
 
 # different target?
 #env.Program('messaging/demo', ['messaging/demo.cc'], LIBS=[messaging_lib, 'zmq'])