.github: add OpenBSD build

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

.github/workflows/build-xserver.yml

@@ -599,6 +599,65 @@ jobs:
                   usesh: true
                   run:     ./.github/scripts/solaris/run-xserver-build.sh
 
+    # OpenBSD build, run in an OpenBSD VM (vmactions, same mechanism as the
+    # other BSD jobs). OpenBSD ships X.Org (xenocara) in base, so only build
+    # tooling is installed; X libs (incl. Mesa) come from /usr/X11R6. glx stays
+    # enabled (indirect/software GLX against the base Mesa); dri2/dri3 stay off
+    # (direct rendering needs a working DRM/KMS, n/a in the headless VM).
+    # werror off while the platform is freshly added.
+    xserver-build-openbsd:
+        runs-on: ubuntu-latest
+        needs: ubuntu-fetch-pkg
+        timeout-minutes: 90
+        env:
+            MESON_ARGS: -Dwerror=false -Dxvfb=true -Dxnest=true -Dxorg=false -Dxephyr=false -Dxfbdev=false -Ddri2=false -Ddri3=false
+        steps:
+            - uses: actions/checkout@v6
+            - uses: ./.github/actions/ubuntu-pkg-cache
+
+            # VM boot / image provisioning flakes transiently; retry the whole
+            # VM step up to 3x, tearing down the leftover domain between tries
+            # (see .github/actions/libvirt-cleanup). Only the last attempt is
+            # allowed to fail the job; a success short-circuits the rest.
+            - name: run in OpenBSD VM (attempt 1)
+              id: openbsd-1
+              continue-on-error: true
+              uses: vmactions/openbsd-vm@v1
+              with:
+                  envs: 'MESON_ARGS'
+                  usesh: true
+                  run:     ./.github/scripts/openbsd/run-xserver-build.sh
+
+            - name: cleanup stale VM before retry
+              if: steps.openbsd-1.outcome == 'failure'
+              uses: ./.github/actions/libvirt-cleanup
+              with:
+                  guest: openbsd
+
+            - name: run in OpenBSD VM (attempt 2)
+              id: openbsd-2
+              if: steps.openbsd-1.outcome == 'failure'
+              continue-on-error: true
+              uses: vmactions/openbsd-vm@v1
+              with:
+                  envs: 'MESON_ARGS'
+                  usesh: true
+                  run:     ./.github/scripts/openbsd/run-xserver-build.sh
+
+            - name: cleanup stale VM before final retry
+              if: steps.openbsd-1.outcome == 'failure' && steps.openbsd-2.outcome == 'failure'
+              uses: ./.github/actions/libvirt-cleanup
+              with:
+                  guest: openbsd
+
+            - name: run in OpenBSD VM (attempt 3)
+              if: steps.openbsd-1.outcome == 'failure' && steps.openbsd-2.outcome == 'failure'
+              uses: vmactions/openbsd-vm@v1
+              with:
+                  envs: 'MESON_ARGS'
+                  usesh: true
+                  run:     ./.github/scripts/openbsd/run-xserver-build.sh
+
     xserver-build-alpine:
         runs-on: ubuntu-latest
         needs: ubuntu-fetch-pkg