[llvm] [Support] Fix the issue where the character being saved in Unicode causes a warning to be treated as an error in Visual Studio 2022. (PR #88513)

[Joseph Huber via llvm-commits]

================
@@ -57,7 +57,7 @@ class ThreadPoolExecutor : public Executor {
     Threads.resize(1);
     std::lock_guard<std::mutex> Lock(Mutex);
     // Use operator[] before creating the thread to avoid data race in .size()
-    // in “safe libc++” mode.
+    // in "safe libc++" mode.
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jhuber6 wrote:

```suggestion
    // in 'safe libc++' mode.
```
Single quotes are more common for stuff like this.

https://github.com/llvm/llvm-project/pull/88513