[lit] Factor out a results consumer interface for test execution.
 - Also, change TestProvider interface to operate on test indices.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189552 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Put display lock inside the ThreadResultsConsumer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189553 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Refactor test execution logic into lit.run.Run.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189554 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Implement --max-time support by using provider cancel method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189555 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Add support for multiprocessing, under --use-processes for now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189556 91177308-0d34-0410-b5e6-96231b3b80d8