llvm-ar: Clean up memory management with OwningPtr.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186131 91177308-0d34-0410-b5e6-96231b3b80d8
Add the ability to use guarded malloc when running llvm lit tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186134 91177308-0d34-0410-b5e6-96231b3b80d8