[llvm] [docker][Windows] install libxml2 using vcpkg (PR #209422)

[Charles Zablit via llvm-commits]

https://github.com/charles-zablit created https://github.com/llvm/llvm-project/pull/209422

Since https://github.com/llvm/llvm-project/pull/209258, lldb uses `lldb-server.exe` by default if libxml2 is available at build time. This means that lldb-server requires installing libxml2 in the CI environments to test it.

This patch adds a step to install libxml2 in the docker container used for lldb pre-merge testing on Windows.

>From 213ecf895ad8706c5aaaedc4a9eee2d8b50c66a7 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Tue, 14 Jul 2026 10:52:31 +0100
Subject: [PATCH] [docker][Windows] install libxml2 using vcpkg

---
 .../workflows/containers/github-action-ci-windows/Dockerfile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/.github/workflows/containers/github-action-ci-windows/Dockerfile b/.github/workflows/containers/github-action-ci-windows/Dockerfile
index a6d3fd195e731..10cae1a98e48f 100644
--- a/.github/workflows/containers/github-action-ci-windows/Dockerfile
+++ b/.github/workflows/containers/github-action-ci-windows/Dockerfile
@@ -48,6 +48,11 @@ RUN choco install -y ninja --version 1.13.1 && \
     choco install -y python3 --version 3.12.3 && \
     choco install -y make --version 4.4.1
 
+# Install libxml2 using vcpkg.
+RUN git clone --depth 1 --branch 2026.06.24 https://github.com/microsoft/vcpkg.git C:\vcpkg && \
+    C:\vcpkg\bootstrap-vcpkg.bat -disableMetrics && \
+    C:\vcpkg\vcpkg.exe install libxml2:x64-windows
+
 # Testing requires psutil
 RUN pip install psutil