[libxml2]Add libxml2 library

libxml2/.gitlab-ci/setup_mingw.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+pacman --noconfirm -Syu
+
+prefix=
+if [ -n "$MINGW_PACKAGE_PREFIX" ]; then
+    prefix="${MINGW_PACKAGE_PREFIX}-"
+fi
+for module in docbook-xsl doxygen libiconv python xsltproc xz zlib "$@"; do
+    pacman --noconfirm -S --needed ${prefix}$module
+done
+
+mkdir -p libxml2-build
+
+if [ ! -e xmlconf ]; then
+    wget https://www.w3.org/XML/Test/xmlts20080827.tar -O - |
+       tar -x
+fi