Allow for yet another crash symptom in 013_crash_restart.pl.

Given the right timing, psql could emit "connection to server was lost"
rather than one of the other messages that this test script checked for.
It looks like commit 4247db62 may have made this more likely, but
I don't really believe it was impossible before then.  Rather than
stress about it, just add that spelling as one of the crash-successfully-
detected cases.

Discussion: https://postgr.es/m/19344.1548554028@sss.pgh.pa.us

src/test/recovery/t/013_crash_restart.pl

@@ -115,7 +115,7 @@ SELECT 1;
 ok( pump_until(
 		$killme,
 		\$killme_stderr,
-		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly/m
+		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly|connection to server was lost/m
 	),
 	"psql query died successfully after SIGQUIT");
 $killme_stderr = '';
@@ -128,7 +128,7 @@ $killme->finish;
 ok( pump_until(
 		$monitor,
 		\$monitor_stderr,
-		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly/m
+		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly|connection to server was lost/m
 	),
 	"psql monitor died successfully after SIGQUIT");
 $monitor->finish;
@@ -197,7 +197,7 @@ SELECT 1;
 ];
 ok( pump_until(
 		$killme, \$killme_stderr,
-		qr/server closed the connection unexpectedly/m),
+		qr/server closed the connection unexpectedly|connection to server was lost/m),
 	"psql query died successfully after SIGKILL");
 $killme->finish;
 
@@ -207,7 +207,7 @@ $killme->finish;
 ok( pump_until(
 		$monitor,
 		\$monitor_stderr,
-		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly/m
+		qr/WARNING:  terminating connection because of crash of another server process|server closed the connection unexpectedly|connection to server was lost/m
 	),
 	"psql monitor died successfully after SIGKILL");
 $monitor->finish;