Unittests/Support/Path: Tweak test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123546 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Support/Path.cpp b/unittests/Support/Path.cpp
index fa2b45f..1f67f13 100644
--- a/unittests/Support/Path.cpp
+++ b/unittests/Support/Path.cpp
@@ -230,7 +230,7 @@
     ASSERT_FALSE(file.has_error());
     StringRef magic(i->magic_str, i->magic_str_len);
     file << magic;
-    file.flush();
+    file.close();
     bool res = false;
     ASSERT_NO_ERROR(fs::has_magic(file_pathname.c_str(), magic, res));
     EXPECT_TRUE(res);