[lit] Add a test suite for lit itself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173999 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Add a script for checking test coverage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174000 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Add a basic discovery test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174001 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Add a MANIFEST file and a script for sanity checking the source dist.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174002 91177308-0d34-0410-b5e6-96231b3b80d8