ci: add GHA workflow for MSYS2 build

Author: striezel

.github/workflows/msys2.yml

@@ -0,0 +1,39 @@
+name: MSYS2
+
+on: push
+
+jobs:
+  msys2_mingw64:
+    runs-on: windows-2022
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+      # Checks-out the repository under $GITHUB_WORKSPACE.
+      - uses: actions/checkout@v3
+        with:
+          submodules: 'recursive'
+      - uses: msys2/setup-msys2@v2
+        with:
+          msystem: mingw64
+          update: true
+          install: >-
+            mingw-w64-x86_64-cmake
+            mingw-w64-x86_64-gcc
+            mingw-w64-x86_64-make
+            mingw-w64-x86_64-ninja
+      - name: Build
+        run: |
+          export MSYSTEM=MINGW64
+          export CXX=g++
+          export CC=gcc
+          cd $GITHUB_WORKSPACE
+          mkdir build
+          cd build
+          cmake ../
+          cmake --build . -j2
+      - name: Run tests
+        run: |
+          export MSYSTEM=MINGW64
+          cd "$GITHUB_WORKSPACE/build"
+          ctest -V

readme.md

@@ -2,6 +2,7 @@
 
 [![GitHub GCC status](https://github.com/striezel/secure-hash-algorithm/workflows/GCC/badge.svg)](https://github.com/striezel/secure-hash-algorithm/actions)
 [![GitHub Clang status](https://github.com/striezel/secure-hash-algorithm/workflows/Clang/badge.svg)](https://github.com/striezel/secure-hash-algorithm/actions)
+[![GitHub MSYS2 status](https://github.com/striezel/secure-hash-algorithm/workflows/MSYS2/badge.svg)](https://github.com/striezel/secure-hash-algorithm/actions)
 [![GitLab pipeline status](https://gitlab.com/striezel/secure-hash-algorithm/badges/master/pipeline.svg)](https://gitlab.com/striezel/secure-hash-algorithm/-/pipelines)
 
 ## Purpose of the program