Remove dead function user_cache_directory()

It's been unused since it was added almost 3 years ago in
https://reviews.llvm.org/D13801

Motivated by https://reviews.llvm.org/rL342002 since it removes one of the
functions keeping a ref to SHGetKnownFolderPath.

Differential Revision: https://reviews.llvm.org/D52184


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342485 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed