misc: Expose the listener loopbackOnly function to python.

Change-Id: Ibb405af54a46a93706a6f476b5314491e84be0c8
Reviewed-on: https://gem5-review.googlesource.com/3081
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/python/m5/simulate.py

@@ -368,4 +368,5 @@ def fork(simout="%(parent)s.f%(fork_seq)i"):
     return pid
 
 from _m5.core import disableAllListeners, listenersDisabled
+from _m5.core import listenersLoopbackOnly
 from _m5.core import curTick

src/python/pybind11/core.cc

@@ -234,6 +234,7 @@ pybind_init_core(py::module &m_native)
 
         .def("disableAllListeners", &ListenSocket::disableAll)
         .def("listenersDisabled", &ListenSocket::allDisabled)
+        .def("listenersLoopbackOnly", &ListenSocket::loopbackOnly)
         .def("seedRandom", [](uint64_t seed) { random_mt.init(seed); })