server: assume PID is dead on ESRCH

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/server.c b/server.c
index 339bb66..e6c49cc 100644
--- a/server.c
+++ b/server.c
@@ -1008,7 +1008,7 @@
 
 	pid = atoi(buf);
 	if (kill(pid, SIGCONT) < 0)
-		return 0;
+		return errno != ESRCH;
 
 	return 1;
 }