Rearrangements to the receive thread.

Magnitude conversion now happens immediately when sample data is
received, so there is no risk of newly received data clobbering old
data under CPU overload.

net_io.c

@@ -825,14 +825,14 @@ static char * appendStatsJson(char *p,
 
     if (!Modes.net_only) {
         p += snprintf(p, end-p,
-                      ",\"local\":{\"blocks_processed\":%u"
-                      ",\"blocks_dropped\":%u"
+                      ",\"local\":{\"samples_processed\":%llu"
+                      ",\"samples_dropped\":%llu"
                       ",\"modeac\":%u"
                       ",\"modes\":%u"
                       ",\"bad\":%u"
                       ",\"unknown_icao\":%u",
-                      st->blocks_processed,
-                      st->blocks_dropped,
+                      (unsigned long long)st->samples_processed,
+                      (unsigned long long)st->samples_dropped,
                       st->demod_modeac,
                       st->demod_preambles,
                       st->demod_rejected_bad,