Cope gracefully with the inability to fopen pool.status file.

src/stratifier.c

@@ -8300,6 +8300,7 @@ static void *statsupdate(void *arg)
 		s = json_dumps(val, JSON_NO_UTF8 | JSON_PRESERVE_ORDER);
 		json_decref(val);
 		LOGNOTICE("Pool:%s", s);
+		if (likely(fp))
 			fprintf(fp, "%s\n", s);
 		dealloc(s);
 
@@ -8314,6 +8315,7 @@ static void *statsupdate(void *arg)
 		s = json_dumps(val, JSON_NO_UTF8 | JSON_PRESERVE_ORDER);
 		json_decref(val);
 		LOGNOTICE("Pool:%s", s);
+		if (likely(fp))
 			fprintf(fp, "%s\n", s);
 		dealloc(s);
 
@@ -8325,9 +8327,11 @@ static void *statsupdate(void *arg)
 		s = json_dumps(val, JSON_NO_UTF8 | JSON_PRESERVE_ORDER | JSON_REAL_PRECISION(3));
 		json_decref(val);
 		LOGNOTICE("Pool:%s", s);
+		if (likely(fp)) {
 			fprintf(fp, "%s\n", s);
-		dealloc(s);
 			fclose(fp);
+		}
+		dealloc(s);
 
 		if (ckp->proxy && sdata->proxy) {
 			proxy_t *proxy, *proxytmp, *subproxy, *subtmp;