Correct comment about behaviour of forward_list::resize in impls

Author: jwakely

xml/issue4164.xml

@@ -102,7 +102,7 @@ there <del>shall be</del> <ins>is</ins> no effect
 The proposed resolution potentially mandates a change to `resize` when
 increasing the size, requiring implementations to "roll back" earlier
 insertions if a later one throws, so that the size is left unchanged.
-It appears that all of libstdc++, libc++ and MSVC already do this.
+It appears that libstdc++ and MSVC already do this, libc++ does not.
 </p>
 
 <note>2024-10-09; LWG telecon: Move to Ready</note>