[clang] [BitInt] Expose a _BitInt literal suffix in C++ (PR #86586)

[Aaron Ballman via cfe-commits]

================
@@ -80,7 +80,10 @@ class NumericLiteralParser {
   bool isFloat128 : 1;      // 1.0q
   bool isFract : 1;         // 1.0hr/r/lr/uhr/ur/ulr
   bool isAccum : 1;         // 1.0hk/k/lk/uhk/uk/ulk
-  bool isBitInt : 1;        // 1wb, 1uwb (C23)
+  // clang-format off
+  bool isBitInt : 1;        // 1wb, 1uwb (C23) or 1__wb, 1__uwb (Clang extension in C++
+                            // mode)
+  // clang-format on
----------------
AaronBallman wrote:

```suggestion
  bool isBitInt : 1;        // 1wb, 1uwb (C23) or 1__wb, 1__uwb (Clang extension in C++
                            // mode)
```
It's fine for the patch to not be clang-format clean instead of cluttering source with clang format comments.

https://github.com/llvm/llvm-project/pull/86586