[llvm-ar][test] Relax lit directory assumptions in thin-archive.test
Summary: thin-archive.test assumes the Output/<testname> structure that lit creates. Rewrite the test in a way that still tests the same thing (creating via relative path and adding via absolute path) but doesn't assume this specific lit structure, making it possible to run in a lit emulator.
Reviewers: gbreynoo
Reviewed By: gbreynoo
Subscribers: llvm-commits, bkramer
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62930
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363189
91177308-0d34-0410-b5e6-
96231b3b80d8