Do not include buildslave name in Polly's LNT results

This allows us to run the same nightly tests on different servers. Which
means we can afford to run with more iterations and on a shorter list
of commits.

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@198295 91177308-0d34-0410-b5e6-96231b3b80d8