[llvm] [NFC][ADT/Support] Add {} for else when if body has {} (PR #140758)

[Saleem Abdulrasool via llvm-commits]

================
@@ -885,8 +885,9 @@ double APInt::roundToDouble(bool isSigned) const {
     if (isSigned) {
       int64_t sext = SignExtend64(getWord(0), BitWidth);
       return double(sext);
-    } else
+    } else {
       return double(getWord(0));
+    }
----------------
compnerd wrote:

```suggestion
    }
    return double(getWord(0));
```

https://github.com/llvm/llvm-project/pull/140758