Include st_dev to make the result of getUniqueID actually unique.

This will let us use getUniqueID instead of st_dev directly on clang.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187378 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Path.cpp b/lib/Support/Path.cpp
index 6d10c0e..cfd9ed6 100644
--- a/lib/Support/Path.cpp
+++ b/lib/Support/Path.cpp
@@ -638,6 +638,15 @@
 
 namespace fs {
 
+error_code getUniqueID(const Twine Path, UniqueID &Result) {
+  file_status Status;
+  error_code EC = status(Path, Status);
+  if (EC)
+    return EC;
+  Result = Status.getUniqueID();
+  return error_code::success();
+}
+
 error_code createUniqueFile(const Twine &Model, int &ResultFd,
                             SmallVectorImpl<char> &ResultPath, unsigned Mode) {
   return createUniqueEntity(Model, ResultFd, ResultPath, false, Mode, FS_File);