Do rollover daily stats (dsts.ini) if the previous date was Jan-1-1970 (never)

Basically revert commit 2064f3a4

In a new install, the "Date" value in dsts.ini will be 0/Never and thus would
never be rolled over (e.g. stats moved o csts.tab files).

Since getstats() now reliably detects any read failures, we shouldn't need
this as a work-around any more anyway - if the "date" field is 0, it just
means a new install and it's expected.

This should fix the issue reported by Basis where the ctrl/csts.tab and
node*/csts.tab files were never created in fresh install of v3.20. A work
around is to just set the Date field in the ctrl/dsts.ini file to the current
date (one time).

src/sbbs3/logon.cpp

@@ -629,7 +629,6 @@ uint sbbs_t::logonstats()
 		return 0;
 	}
 
-	if (stats.date != 0) {
 	now = time(NULL);
 	if (stats.date > now + (24L * 60L * 60L)) /* More than a day in the future? */
 		errormsg(WHERE, ERR_CHK, "Daily stats date/time stamp", (ulong)stats.date);
@@ -687,7 +686,6 @@ uint sbbs_t::logonstats()
 			fclose_cstats(csts);
 		}
 	}
-	}
 	if (cfg.node_num == 0) /* called from event_thread() */
 		return 0;