[MINOR] move the initial task's nice value to the listener

Since the listener is the one indicating what analyser and session
handlers to call, it makes sense that it also sets the task's nice
value. This also helps getting rid of the last trace of the stats
in the proto_uxst file.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 91c90e9..24aab05 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -121,6 +121,7 @@
 		global.stats_sock.accept = uxst_event_accept;
 		global.stats_sock.handler = process_session;
 		global.stats_sock.analysers = AN_REQ_STATS_SOCK;
+		global.stats_sock.nice = -64;  /* we want to boost priority for local stats */
 		global.stats_sock.private = global.stats_fe; /* must point to the frontend */
 
 		global.stats_fe->timeout.client = MS_TO_TICKS(10000); /* default timeout of 10 seconds */