[lit] Change lit.Test.ResultCode to be unique across pickling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189549 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Factor out Run class to capture configuration + discovered tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189550 91177308-0d34-0410-b5e6-96231b3b80d8