Checkmk Werk 10181: local: Fix "Invalid performance data" on trailing semicolons

ID: 10181 Title: local: Fix "Invalid performance data" on trailing semicolons Component: Checks & agents Level: 1 Class: Bug fix Version: 1.7.0i1 When a local check reported perfdata that had one or multiple a trailing ";" signs, this could break the local check making it show the message "Invalid performance data".