[clang][NFC] Add a missing comment to #71322 changes

It was an unfortunate oversight from my side to forget to include this comment into the PR.

Author: Endilll

clang/lib/Sema/SemaExprCXX.cpp

@@ -2443,6 +2443,11 @@ ExprResult Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
       FullInit = Binder->getSubExpr();
 
     Initializer = FullInit.get();
+    // We don't know that we're generating an implicit initializer until now, so
+    // we have to update the initialization style as well.
+    //
+    // FIXME: it would be nice to determine the correct initialization style
+    // earlier so InitStyle doesn't need adjusting.
     if (InitStyle == CXXNewInitializationStyle::None && Initializer) {
       InitStyle = CXXNewInitializationStyle::Implicit;
     }