Crash on StatsDAgent on resource-constrained box with load

[santigimeno]

Observed when running test-nsolid-start-statsd.js

* thread #1, name = 'nsolid', stop reason = signal SIGABRT
  * frame #0: 0x00007eff3b44c9fc libc.so.6`__GI___pthread_kill at pthread_kill.c:44:76
    frame #1: 0x00007eff3b44c9b0 libc.so.6`__GI___pthread_kill [inlined] __pthread_kill_internal(signo=6, threadid=139634419955264) at pthread_kill.c:78:10
    frame #2: 0x00007eff3b44c9b0 libc.so.6`__GI___pthread_kill(threadid=139634419955264, signo=6) at pthread_kill.c:89:10
    frame #3: 0x00007eff3b3f8476 libc.so.6`__GI_raise(sig=6) at raise.c:26:13
    frame #4: 0x00007eff3b3de7f3 libc.so.6`__GI_abort at abort.c:79:7
    frame #5: 0x000055897bd965c9 nsolid`node::nsolid::statsd::StatsDUdp::write_cb_(req=0x00007eff20007850, status=-125, udp=0x00007eff20004a00) at statsd_agent.cc:267:5
    frame #6: 0x000055897bda3bfa nsolid`void nsuv::ns_udp::send_proxy_<void (*)(nsuv::ns_udp_send*, int, node::nsolid::statsd::StatsDUdp*), node::nsolid::statsd::StatsDUdp>(uv_req=0x00007eff20007850, status=-125) at nsuv-inl.h:1581:6
    frame #7: 0x000055897d10e8bc nsolid`uv__udp_run_completed(handle=0x00007eff200017b0) at udp.c:121:7
    frame #8: 0x000055897d10e67f nsolid`uv__udp_finish_close(handle=0x00007eff200017b0) at udp.c:79:3
    frame #9: 0x000055897d0f7fe5 nsolid`uv__finish_close(handle=0x00007eff200017b0) at core.c:338:7
    frame #10: 0x000055897d0f80d9 nsolid`uv__run_closing_handles(loop=0x00005589822d6dc0) at core.c:364:5
    frame #11: 0x000055897d0f83fb nsolid`uv_run(loop=0x00005589822d6dc0, mode=UV_RUN_DEFAULT) at core.c:468:5
    frame #12: 0x000055897bd97a3d nsolid`node::nsolid::statsd::StatsDAgent::run_((null)=0x00005589822d7110, agent=0x00005589822d6dc0) at statsd_agent.cc:421:5
    frame #13: 0x000055897bda41b8 nsolid`void nsuv::ns_thread::create_proxy_<void (*)(nsuv::ns_thread*, node::nsolid::statsd::StatsDAgent*), node::nsolid::statsd::StatsDAgent>(arg=0x00005589822d7110) at nsuv-inl.h:1829:6
    frame #14: 0x00007eff3b44aac3 libc.so.6`start_thread(arg=<unavailable>) at pthread_create.c:442:8
    frame #15: 0x00007eff3b4dbbf4 libc.so.6`__clone at clone.S:100