amari.xlog: Begin emitting queries right after startup

For example with `stats/100s` stats query is emitted every 100 seconds,
but currently it will be first emitted only after waiting for 100
seconds after `xamari xlog` startup, or after reconnection to eNB if eNB
itself was restarted. And this way it will be hard to interpret obtained
numbers in relation to last 100s time interval.

-> Start emitting queries right after reconnection / xlog start, so that
we see the values as observed at the beginning, and can compare result
of further queries to them.

amari/xlog.py

@@ -171,9 +171,7 @@ class _XLogger:
 
         # loop emitting requested logspecs
         t0 = time.now()
-        tnextv = []     # [i] - next time to arm for logspecv[i] relative to t0
-        for l in xl.logspecv:
-            tnextv.append(l.period)
+        tnextv = [0]*len(xl.logspecv)   # [i] - next time to arm for logspecv[i] relative to t0
 
         while 1:
             # go through all logspecs in the order they were given