Ensure we are closing current log file before entering next log file

Signed-off-by: Claudio Cambra <claudio.cambra@nextcloud.com>

src/libsync/logger.cpp

@@ -119,6 +119,7 @@ void Logger::doLog(QtMsgType type, const QMessageLogContext &ctx, const QString
 #endif
     {
         if (_logFile.size() >= MaxLogSizeBytes) {
+            close();
             enterNextLogFile();
         }