[vcpkg] Fix build under /W4

I was building under /W3, because CMake hadn't been set up to build
under /W4 -- therefore, I didn't see some warnings.

We also decided to remove the niebloids and instead break ADL by using
`= delete`, since otherwise we get warnings when we define a local
variable with the same name as a niebloid. I also removed `status` and
`symlink_status` from the `files` header, since it's unnecessary now,
and they're just implementation details of `RealFilesystem`.

I also removed some existing uses of unqualified `status(path)`, since
that no longer compiles. I also added `Filesystem::canonical`, to remove
another use of `fs::stdfs` in a function I was already working in.

0 files changed, 0 insertions, 0 deletions