[mlir] Improve line breaks of code snippets in comments (NFC).

[ingomueller-net]

White-space-in-comments only change and builds passing: self-accepting.

mlir/include/mlir/Transforms/DialectConversion.h

return wrapCallback<T>(
             bool wasSuccess = static_cast<bool>(*resultOpt);
             if (wasSuccess)
               results.push_back(*resultOpt);
             return std::optional<LogicalResult>(success(wasSuccess));
           }
           return std::optional<LogicalResult>();
         });
   }
-  /// With callback of form: `std::optional<LogicalResult>(T,
-  /// SmallVectorImpl<Type>
-  /// &)`
+  /// With callback of form: `std::optional<LogicalResult>(
+  ///     T, SmallVectorImpl<Type> &)`.
   template <typename T, typename FnT>
   std::enable_if_t<std::is_invocable_v<FnT, T, SmallVectorImpl<Type> &>,
                    ConversionCallbackFn>
   wrapCallback(FnT &&callback) {
     return wrapCallback<T>(
         [callback = std::forward<FnT>(callback)](
             T type, SmallVectorImpl<Type> &results, ArrayRef<Type>) {
           return callback(type, results);
         });
   }
-  /// With callback of form: `std::optional<LogicalResult>(T,
-  /// SmallVectorImpl<Type>
-  /// &, ArrayRef<Type>)`.
+  /// With callback of form: `std::optional<LogicalResult>(
+  ///     T, SmallVectorImpl<Type> &, ArrayRef<Type>)`.
   template <typename T, typename FnT>
   std::enable_if_t<
       std::is_invocable_v<FnT, T, SmallVectorImpl<Type> &, ArrayRef<Type>>,
       ConversionCallbackFn>
   wrapCallback(FnT &&callback) {
     return [callback = std::forward<FnT>(callback)](
                Type type, SmallVectorImpl<Type> &results,
                ArrayRef<Type> callStack) -> std::optional<LogicalResult> {