This fixes a unit test. Otherwise here is the original commit:
1) Shared writable directories like /tmp are a security problem.
2) Systems provide dedicated cache directories these days anyway.
3) This also refines LLVM's cache_directory() on Darwin platforms to use
the Darwin per-user cache directory.
Reviewers: compnerd, aprantl, jakehehrlich, espindola, respindola, ilya-biryukov, pcc, sammccall
Reviewed By: compnerd, sammccall
Subscribers: hiraditya, llvm-commits, cfe-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D82362