Merge PR #22315: Fix Windows CI: work around Cygwin pkgconf 3.0.4-1 personality path bug

Reviewed-by: SkySkimmer
Co-authored-by: SkySkimmer <[email protected]>

Author: coqbot-app[bot]

.github/workflows/ci-github.yml

@@ -55,6 +55,20 @@ jobs:
           ocaml-compiler: ${{ matrix.ocaml }}
           dune-cache: true
 
+      # Cygwin's pkgconf 3.0.4-1 (2026-07-26) compiles its personality search
+      # path as /usr/lib/pkgconfig/personality.d:/usr/share/pkgconfig/personality.d
+      # but still installs the mingw-w64 personality files under
+      # /etc/pkgconfig/personality.d, so `pkgconf --personality=<triplet>`
+      # silently falls back to the native personality and the
+      # conf-mingw-w64-{gmp,zlib}-* opam packages fail their probes.  pkgconf
+      # also searches $XDG_DATA_DIRS/pkgconfig/personality.d, so prepending /etc
+      # restores the lookup.  Drop this once Cygwin ships a fixed pkgconf
+      # packaging.
+      - name: 🩹 Work around Cygwin pkgconf 3.0.4-1 personality path bug
+        if: matrix.os == 'windows-latest'
+        run: |
+          "XDG_DATA_DIRS=/etc:/usr/local/share:/usr/share" >> $env:GITHUB_ENV
+
       - name: 🐫🐪🐫 Get Rocq dependencies
         run: opam install --deps-only ${{ matrix.packages }}