[llvm] Update FileSystem test that failed spuriously

This test failed spuriously in an environment that appears to ignore the
'x' bit permission on directories. Allow for that possibility.

(cherry picked from commit cf1521e)

Author: benlangmuir

llvm/unittests/Support/Path.cpp

@@ -828,15 +828,14 @@ TEST_F(FileSystemTest, RemoveDirectoriesNoExePerm) {
 
   ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
                                          /*IgnoreErrors=*/true));
-  ASSERT_TRUE(fs::exists(Twine(TestDirectory) + "/noexeperm"));
-  ASSERT_EQ(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
-                                   /*IgnoreErrors=*/false),
-            errc::permission_denied);
-
-  fs::setPermissions(Twine(TestDirectory) + "/noexeperm", fs::all_perms);
 
-  ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
-                                         /*IgnoreErrors=*/false));
+  // It's expected that the directory exists, but some environments appear to
+  // allow the removal despite missing the 'x' permission, so be flexible.
+  if (fs::exists(Twine(TestDirectory) + "/noexeperm")) {
+    fs::setPermissions(Twine(TestDirectory) + "/noexeperm", fs::all_perms);
+    ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
+                                           /*IgnoreErrors=*/false));
+  }
 }
 #endif