Add a class to create a tar archive file.

In LLD, we create cpio archive files for --reproduce command.
cpio was not a bad choice because it is very easy to create, but
it was sometimes hard to use because people are not familiar with
cpio command.

I noticed that creating a tar archive isn't as hard as I thought.
So I implemented it in this patch.

Differential Revision: https://reviews.llvm.org/D28091

llvm-svn: 291209