Use "optimization" or shortcuts for dictionary lookups in perf/*.q

This improves throughput of inproc from 400 Mb/s (inproc_thr_nonopt.q) vs 700 Mb/s (inproc_thr.q).
Merge branch 'master' of git://github.com/jaeheum/qzmq

* 'master' of git://github.com/jaeheum/qzmq:
  1.2.0-RC3.
1.2.0-RC4.