[clang] [clang-format] Treat empty for/while loops as short loops (PR #70768)

[Owen Pan via cfe-commits]

================
@@ -3117,9 +3117,16 @@ void UnwrappedLineParser::parseForOrWhileLoop(bool HasParens) {
       FormatTok->setFinalizedType(TT_ConditionLParen);
     parseParens();
   }
-  // Event control.
-  if (Style.isVerilog())
+
+  if (Style.isVerilog()) {
+    // Event control.
     parseVerilogSensitivityList();
+  } else if (Style.AllowShortLoopsOnASingleLine && FormatTok->is(tok::semi) &&
----------------
owenca wrote:

I didn't use `getPreviousNonComment()` because there are 3 more cases where we either can't or probably shouldn't merge the semicolon:

1.
```
while (1) //
  ;
```
2.
```
while (1) /**/
  ;
```
3.
```
while (1)
  /**/ ;
```
Like `while (1) /**/ ;`, case 3 probably doesn't matter in practice.

https://github.com/llvm/llvm-project/pull/70768