Do not modify string returned by getenv on Windows.  Fixes PR9875, patch by Nikola Smiljanic!
Do not modify string returned by getenv on Windows. 
Fixes PR9875, patch by Nikola Smiljanic!

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@135356 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang