Mirror Arch Linux's linux PKGBUILD

They have also put their Gitlab behind Anubis so attempting to fetch the
Arch Linux configuration during the build stage fails.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: nathanchance

.github/workflows/mirror.yml

@@ -4,6 +4,16 @@ on:
     - cron: "0 */6 * * *"
   workflow_dispatch:
 jobs:
+  linux_pkgbuild:
+    name: linux_pkgbuild
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone linux PKGBUILD
+        run: git clone --bare https://gitlab.archlinux.org/archlinux/packaging/packages/linux.git .
+      - name: Mirror linux PKGBUILD
+        run: git push --mirror "https://token:$MIRRORING_TOKEN@github.com/ClangBuiltLinux/linux_pkgbuild.git"
+        env:
+          MIRRORING_TOKEN: ${{ secrets.MIRRORING_TOKEN }}
   rpms_kernel:
     name: rpms/kernel
     runs-on: ubuntu-latest