[libcxx] [llvm] [libc++] Use GitHub-provided runners for the windows CI (PR #79326)

[Nikolas Klauser via llvm-commits]

https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/79326

>From 491798409d238a256362d023f6c3c41168f9c6c0 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Wed, 24 Jan 2024 17:42:53 +0100
Subject: [PATCH] [libc++] Use GitHub-provided runners for the windows CI

---
 .github/workflows/libcxx-build-and-test.yaml | 13 +++++++++++++
 libcxx/trigger                               |  0
 2 files changed, 13 insertions(+)
 create mode 100644 libcxx/trigger

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 5727b956dc6dd2..25ed77bc9ba5a2 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -199,3 +199,16 @@ jobs:
             **/CMakeError.log
             **/CMakeOutput.log
             **/crash_diagnostics/*
+  windows:
+    runs-on: windows-2019
+    steps:
+      - uses: actions/checkout at v4
+      - name: Install dependencies
+        run: choco install -y ninja wget
+        run: wget https://github.com/mstorsjo/llvm-mingw/releases/download/20231128/llvm-mingw-20231128-ucrt-x86_64.zip -O llvm-mingw.zip
+        run: powershell Expand-Archive llvm-mingw.zip -DestinationPath .
+        run: del llvm-mingw.zip
+        run: ren llvm-mingw-20231128-ucrt-x86_64 llvm-mingw
+        run: setx path "%path%;%cd%\llvm-mingw\bin"
+      - name: clang-cl (DLL)
+        run: bash libcxx/utils/ci/run-buildbot clang-cl-dll
diff --git a/libcxx/trigger b/libcxx/trigger
new file mode 100644
index 00000000000000..e69de29bb2d1d6