CI: enable additional Linux distributions

The issues causing Amazon Linux 2 and Debian Bookworm to be unusable in GitHub actions have been corrected.

Author: jakepetroules

.github/scripts/linux_pre_build.sh

@@ -13,7 +13,7 @@
 
 set -e
 
-if command -v apt-get >/dev/null 2>&1 ; then # bookworm, noble, jammy
+if command -v apt-get >/dev/null 2>&1 ; then # bookworm, noble, jammy, focal
     export DEBIAN_FRONTEND=noninteractive
 
     apt-get update -y
@@ -31,16 +31,16 @@ if command -v apt-get >/dev/null 2>&1 ; then # bookworm, noble, jammy
     # Android NDK
     dpkg_architecture="$(dpkg --print-architecture)"
     if [[ "$SKIP_ANDROID" != "1" ]] && [[ "$dpkg_architecture" == amd64 ]] ; then
-        eval "$(cat /etc/lsb-release)"
-        case "$DISTRIB_CODENAME" in
-            bookworm|jammy)
+        eval "$(cat /etc/os-release)"
+        case "$VERSION_CODENAME" in
+            bookworm|jammy|focal)
                 : # Not available
                 ;;
             noble)
                 apt-get install -y google-android-ndk-r26c-installer
                 ;;
             *)
-                echo "Unknown distribution: $DISTRIB_CODENAME" >&2
+                echo "Unable to fetch Android NDK for unknown Linux distribution: $VERSION_CODENAME" >&2
                 exit 1
         esac
     else

.github/workflows/pull_request.yml

@@ -13,7 +13,7 @@ jobs:
     name: Test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
-      linux_os_versions: '["noble", "jammy", "rhel-ubi9"]'
+      linux_os_versions: '["amazonlinux2", "bookworm", "noble", "jammy", "focal", "rhel-ubi9"]'
       linux_pre_build_command: ./.github/scripts/linux_pre_build.sh
       linux_build_command: 'swift test --no-parallel'
       linux_swift_versions: '["nightly-main", "nightly-6.2"]'