Try to setup Github Actions (again)

We originally stopped using it because we were running into the disk space limit, but the builds were much faster with it. I've recently stumbled into a neat trick that should let us have more disk space on the runners.

In addition, this commit also moves the darling-swift repository away from LFS. Note that it is now necessary to run a post-checkout script.

.github/workflows/actions.yaml

@@ -0,0 +1,70 @@
+name: Darling CI
+
+on: [push]
+
+jobs:
+  build-deb:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Checkout submodules
+      shell: bash
+      run: |
+        git submodule update --init --recursive --depth=1
+
+    - name: Post-checkout script
+      run: |
+        ./tools/post-checkout.sh
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get update && sudo apt-get install devscripts equivs debhelper
+        sudo mk-build-deps -i -r -t "apt-get --no-install-recommends -y" debian/control
+
+    # see https://github.com/actions/virtual-environments/issues/2606#issuecomment-772683150
+    - name: Free up space
+      run: |
+        sudo rm -rf /usr/share/dotnet
+
+    - name: Build DEBs
+      run: |
+        ./tools/debian/make-deb
+
+    - name: Move DEBs
+      run: |
+        mkdir dist && mv ../*.deb dist
+
+    - name: Upload artifacts
+      uses: actions/upload-artifact@v1
+      with:
+        name: 'debs'
+        path: dist/
+
+  build-dsc:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Checkout submodules
+      shell: bash
+      run: |
+        git submodule update --init --recursive --depth=1
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get update && sudo apt-get install devscripts equivs debhelper
+
+    - name: Build DSCs
+      run: |
+        ./tools/debian/make-deb --dsc
+
+    - name: Move DSCs
+      run: |
+        mkdir source && mv ../*~$(lsb_release -cs).* source
+
+    - name: Upload artifacts
+      uses: actions/upload-artifact@v1
+      with:
+        name: 'source'
+        path: source/

src/external/swift

@@ -1 +1 @@
-Subproject commit 9d723239b3e50149ee3f3c84cbfe6a4ca08c5722
+Subproject commit a713ab13ebffe88923a2066ad8c9133cb4fe8636

tools/post-checkout.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+SCRIPT_DIR="$(dirname "$(readlink -f "$0")")"
+
+"$SCRIPT_DIR/../src/external/swift/post-checkout.sh"