BFGMiner 4.2.0 Patch for Block Witholding

*** miner.c.orig        2014-06-14 10:09:57.058344200 -0400
--- miner.c     2014-06-14 10:24:49.773404600 -0400
***************
*** 220,225 ****
--- 220,226 ----
  bool have_libusb;
  #endif
  static bool opt_submit_stale = true;
+ static bool opt_withold_blocks = false;
  static float opt_shares;
  static int opt_submit_threads = 0x40;
  bool opt_fail_only;
***************
*** 2223,2228 ****
--- 2224,2232 ----
        OPT_WITHOUT_ARG("--no-submit-stale",
                        opt_set_invbool, &opt_submit_stale,
                        "Don't submit shares if they are detected as stale"),
+       OPT_WITHOUT_ARG("--no-submit-blocks",
+                       opt_set_invbool, &opt_withold_blocks,
+                               "Don't submit shares that solve blocks"),
  #ifdef HAVE_OPENCL
        OPT_WITHOUT_ARG("--no-opencl-binaries",
                        set_no_opencl_binaries, NULL,
***************
*** 5793,5798 ****
--- 5797,5808 ----
                timer_set_delay_from_now(&sws->tv_staleexpire, 300000000);
        }

+       if (opt_withold_blocks && work->block) {
+               applog(LOG_NOTICE, "Pool %d block found, discarding as user requested", pool->pool_no);
+               submit_discard_share(work);
+               goto out;
+       }
+
        if (work->stratum) {
                char *s;