[lit] Delete the now-unused SyntaxCheckTest format.
 - Also, kill the pointless LitFormats module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174070 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] TestRunner: Eliminate failDueToStderr argument, which is now unused.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174071 91177308-0d34-0410-b5e6-96231b3b80d8
[lit] Add a test for the various ShTest format features.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174072 91177308-0d34-0410-b5e6-96231b3b80d8