[Support] Remove unit test for fs::is_local
[Support] Remove unit test for fs::is_local

rL295768 introduced this test that fails if LLVM is built and tested on
an NFS share. Delete the test as discussed on the corresponing commit
thread. The only feasible solution would have been to introduce
environment variables and to en/disable the test conditionally.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@297260 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm