Set priority of various threads if possible.

Conflicts:
	cgminer.c

cgminer.c

@@ -4314,6 +4314,30 @@ void zero_stats(void)
 	}
 }
 
+static void set_highprio(void)
+{
+#ifndef WIN32
+	int ret = nice(-10);
+
+	if (!ret)
+		applog(LOG_DEBUG, "Unable to set thread to high priority");
+#else
+	SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST);
+#endif
+}
+
+static void set_lowprio(void)
+{
+#ifndef WIN32
+	int ret = nice(10);
+
+	if (!ret)
+		applog(LOG_INFO, "Unable to set thread to low priority");
+#else
+	SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_LOWEST);
+#endif
+}
+
 #ifdef HAVE_CURSES
 static void display_pools(void)
 {
@@ -4721,6 +4745,7 @@ static void *api_thread(void *userdata)
 
 	RenameThread("api");
 
+	set_lowprio();
 	api(api_thr_id);
 
 	PTH(mythr) = 0L;
@@ -6383,6 +6408,7 @@ void *miner_thread(void *userdata)
 	applog(LOG_DEBUG, "Waiting on sem in miner thread");
 	cgsem_wait(&mythr->sem);
 
+	set_highprio();
 	drv->hash_work(mythr);
 out:
 	drv->thread_shutdown(mythr);
@@ -6661,6 +6687,8 @@ static void *watchpool_thread(void __maybe_unused *userdata)
 
 	RenameThread("watchpool");
 
+	set_lowprio();
+
 	while (42) {
 		struct timeval now;
 		int i;
@@ -6744,6 +6772,7 @@ static void *watchdog_thread(void __maybe_unused *userdata)
 
 	RenameThread("watchdog");
 
+	set_lowprio();
 	memset(&zero_tv, 0, sizeof(struct timeval));
 	cgtime(&rotate_tv);