Backport another libc++ patch for std::filesystem (and locale) usage

This fixes linking against a DLL of libc++ while using the common headers
(generated from the static version of the library, but which work for
both shared and static versions) when calling e.g. std::filesystem::u8path.

patches/llvm-project/0020-libcxx-Avoid-infinite-recursion-in-create_directorie.patch

@@ -1,7 +1,7 @@
 From 6c968da9f1e9281055d31f66c292f81de204924d Mon Sep 17 00:00:00 2001
 From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
 Date: Sat, 27 Feb 2021 19:12:25 +0200
-Subject: [PATCH 20/24] [libcxx] Avoid infinite recursion in
+Subject: [PATCH 20/25] [libcxx] Avoid infinite recursion in
  create_directories, if the root directory doesn't exist
 
 Differential Revision: https://reviews.llvm.org/D97618