Allowed LLVM to be in another directory.
Allowed LLVM to be in another directory.

This allows us to share source checkouts of llvm.
This also significantly speeds up the parsing of includes
using Visual Studio Code.

Change-Id: Idd063b43534e1e26e5b377b8cb9a41d2bc159a5f
Reviewed-on: https://wn-project.dnsalias.net/gerrit/298
Try: Andrew Woloszyn <2926f0436f8103ab8257713335cf26447d8bf68a@google.com>
Tested-by: WNBot <efa0942020584fb66fb8bea377b59e48fa0f85ef@gmail.com>
Reviewed-by: Devon Powell <bef84a74f4a3947934cc58306a6aae518eaf1936@gmail.com>

WNProject/WNFramework,WNProject/WNFramework,WNProject/WNFramework,WNProject/WNFramework