Fix persistent db writing on Windows.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=464779

ChangeLog.txt

@@ -5,6 +5,7 @@ Broker:
 - Fix bridge prefixes only working for the first outgoing message. Closes
   #464437.
 - Fix incorrect bridge connection notifications on local broker.
+- Fix persistent db writing on Windows. Closes #464779.
 
 Client library:
 - Inflight message count wasn't being decreased for outgoing messages using

src/persist.c

@@ -386,7 +386,9 @@ int mqtt3_db_backup(struct mosquitto_db *db, bool shutdown)
 
 #ifdef WIN32
 	if(remove(db->config->persistence_filepath) != 0){
-		goto error;
+		if(errno != ENOENT){
+			goto error;
+		}
 	}
 #endif
 	if(rename(outfile, db->config->persistence_filepath) != 0){