Fix unit tests on Windows: handle env vars with non-ASCII chars.
Fix unit tests on Windows: handle env vars with non-ASCII chars.

Summary: On Windows we have to take UTF16 encoded env vars and convert them to UTF8. This patch fixes CopyEnvironment helper function used by process unit tests.

Reviewers: yaron.keren

Subscribers: yaron.keren, llvm-commits

Differential Revision: http://reviews.llvm.org/D14278

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@252039 91177308-0d34-0410-b5e6-96231b3b80d8

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