[lit] Only send back test result from worker process

Avoid sending back the whole run.Test object (which needs to be pickled)
from the worker process when we are only interested in the test result.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375262 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed