SyncEngine: Calculate a uniq journal name using the remote account.

That should allow to sync the same local folder to multiple remote destinations.

see #3764

src/libsync/syncengine.cpp

@@ -90,8 +90,20 @@ SyncEngine::SyncEngine(AccountPtr account, const QString& localPath,
 #endif
     url_string = Utility::toCSyncScheme(url_string);
 
+    // localPath always has a trailing slash
+    QString dbFile = localPath;
+    dbFile.append( QLatin1String(".csync_"));
+    // FIXME: Make sure this remoteUrlPath is equal to the one calculated in FolderMan::ensureJournalGone
+    // FIXME: Maybe it is better to only allow different hosts, without path component.
+    QString remoteUrlPath = _remoteUrl.toString()+_remotePath;
+    QByteArray ba = QCryptographicHash::hash( remoteUrlPath.toUtf8(), QCryptographicHash::Md5);
+    dbFile.append( ba.left(6).toHex() );
+
+    _journal->setDatabaseFilePath(dbFile);
+
     csync_create(&_csync_ctx, localPath.toUtf8().data(), url_string.toUtf8().data());
-    csync_init(_csync_ctx);
+    csync_init(_csync_ctx, dbFile.toUtf8().data());
+
     _excludedFiles.reset(new ExcludedFiles(&_csync_ctx->excludes));
     _syncFileStatusTracker.reset(new SyncFileStatusTracker(this));