Remove mention of old deleted test scripts from testing guide

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198771 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing test case for r198737.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198772 91177308-0d34-0410-b5e6-96231b3b80d8