Use llvm::sys::path::native instead of llvm::sys::fs::normalize_separators.
Use llvm::sys::path::native instead of llvm::sys::fs::normalize_separators.

llvm::sys::path::native has a superset of the functionality and this was the
only use of llvm::sys::fs::normalize_separators.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@215242 91177308-0d34-0410-b5e6-96231b3b80d8

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