[RFC] Move Virtual File System from clang to llvm

Hi everybody,

I'm working on adding reproducers to LLDB [0] and I'd like to use clang's
virtual file system (VFS), similar to how it is used today for reproducers in
clang. I believe the functionality is generic enough that it warrants living in
support, next to the "real" file system. I can imagine that other tools might
benefit from this functionality as well.

I created a patch [1] to show what this would look like. Most of the changes
are the result of the vfs now living in the llvm namespace.

What do you think?

[0] http://lists.llvm.org/pipermail/lldb-dev/2018-September/014184.html
[1] https://reviews.llvm.org/D52783

I haven’t reviewed the patch in detail, but +1 to the concept!

+1 from me.

Sounds fine to me.