ci: exercise minimal MSYS pacman runtime

Author: frangarcj

.github/workflows/build.yml

@@ -2,6 +2,8 @@ name: Build
 
 on:
   push:
+    branches-ignore:
+      - ci/msys-pacman-smoke
   pull_request:
   repository_dispatch:
     types: [run_build]

.github/workflows/msys-pacman-smoke.yml

@@ -0,0 +1,16 @@
+name: MSYS pacman two-file smoke
+
+on:
+  push:
+    branches:
+      - ci/msys-pacman-smoke
+
+jobs:
+  smoke:
+    runs-on: windows-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Exercise pacman with only the MSYS runtime DLL
+        shell: pwsh
+        run: ./tests/pacman/msys-runtime-smoke.ps1