github actions: Make builds on Merge Request

Since we need to make sure external contributors code actually compiles
prior to merging. To get access to the forked repos merge request we
need to switch over our push to pull_request. In addition we're fixing up
some Naming Conventions, adding aarch64 to this branch and fixing the naming
so that we can quickly identify if the CI is for x86_64.

Also disable the process-pull-request until the `utf-8` situation is
resolved.

.github/workflows/push-check_x86_64.yml → .github/workflows/build-check_x86_64.yml

@@ -1,6 +1,6 @@
-name: CI
+name: x86_64 CI
 on:
-  push:
+  pull_request:
     branches:
       - '**'
       - '!mainline'
@@ -24,10 +24,11 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
         with:
+          ref: "${{ github.event.pull_request.head.sha }}"
           fetch-depth: 0
       - name: Build the Kernel
         run: |
-          git config --global --add safe.directory /__w/kernel-src-git/kernel-src-git
-          cp configs/kernel-4.18.0-x86_64.config .config
+          git config --global --add safe.directory /__w/kernel-src-tree/kernel-src-tree
+          cp configs/kernel-rt-4.18.0-x86_64.config .config
           make olddefconfig
           make -j8