Add AppVeyor continuous integration.

appveyor.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+# AppVeyor Continuous Integration for MSYS2
+# Author: Renato Silva <br.renatosilva@gmail.com>
+
+# Functions
+success() { echo "Build success: ${@}"; exit 0; }
+failure() { echo "Build failure: ${@}"; exit 1; }
+
+# Prepare
+git config --global user.email 'ci@msys2.org'
+git config --global user.name 'MSYS2 AppVeyor CI'
+
+# Recipes
+cd "$(dirname "$0")"
+files=($(git show -m --pretty=format: --name-only))
+for file in "${files[@]}"; do
+    [[ "${file}" = */PKGBUILD ]] && recipes+=("${file}")
+done
+test -n "${files}"   || failure 'could not detect changed files'
+test -z "${recipes}" && success 'no changes in package recipes'
+
+# Build
+for recipe in "${recipes[@]}"; do
+    cd "$(dirname ${recipe})"
+    makepkg-mingw --syncdeps --noconfirm --skippgpcheck || failure "could not build ${recipe}"
+    cd - > /dev/null
+done

appveyor.yml

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+build_script:
+    - C:\msys64\usr\bin\bash --login -c "$(cygpath ${APPVEYOR_BUILD_FOLDER})/appveyor.sh"