[llvm] r309310 - Un-revert "Teach the CMake build system to run lit's test suite. These can be run"

[Brian Gesiak via llvm-commits]

Douglas,

Sorry for the delay, I finally built and ran check-lit using a Visual
Studio configuration. I can confirm I'm also seeing the error.

Victor, perhaps you don't see the error because FileCheck exists on
your system PATH? On my machine, running simply 'FileCheck --help' on
the command line produces an error, unless I pass the full path to
FileCheck.exe.

As for the cause of the issue: I added the following debug statement
to see what was going on:
https://gist.github.com/modocache/20afa965f9d4d53431c8c39e01a7ba34,
and came to the same conclusion you did: the output shows that
"C:/Users/modocache/Source/fb/llvm/build/$(Configuration)/bin" is
being added to my PATH. I imagine "$(Configuration)" here is the
source of the error -- this should have been replaced at some point
with "Debug" or "Release" or something, I expect.

I'll look around at the LLVM CMake to see where "$(Configuration)" is
coming from, or whether it can be expanded somehow.

- Brian