Use LLVM for all stat-related functionality.

This deletes LLDB's FileType enumeration and replaces all
users, and all calls to functions that check whether a file
exists etc with corresponding calls to LLVM.

Differential Revision: https://reviews.llvm.org/D30624

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297116 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed