bs-upload-kernel, MyBS, Buildresults: Support multibuild
    (JSC-SLE#5501, boo#1211226, bsc#1218184)
    
    - strip package name prefix when recording results
    - add package prefix to linked packages
    - when _multibuild file is present do not link packages
    - use onlybuild BuildFlag for limiting build to specific packages
    - generate is_kotd_qa macro in project config that can be used to
      determine if the package is built in the QA repository
    
      This is _very_ convoluted. No shell or lua tools can be used because
      this information needs to be available to the OBS to schedule the
      package in the correct repository, and it does not run scripts. The
      builtin sub macro for slicing strings causes a build error - it
      expanded correctly by the scheduler but not available at package build
      time. If conditional cannot be used because rpm macros from project
      config are added to a macro include file, and those do not support
      conditionals. That leaves the option to use an expression that
      explicitly enumerates all QA repository names. This requires unusal
      and convoluted check in the spec file to make use of.