Cleanup Auxiliary Linux tests (#466)

This PR explictly installs libc and libgcc (to make it clear these are
the only extra dev dependancies).

I also added building/linking of the x32 target. As noted in #464, this
will not run in the current github actions runner due to an incompatible
kernel config.

Signed-off-by: Joe Richey <joerichey@google.com>

Author: josephlr

.github/workflows/tests.yml

@@ -71,20 +71,26 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        target: [
-          x86_64-unknown-linux-musl,
-          i686-unknown-linux-gnu,
-          i686-unknown-linux-musl,
-        ]
+        target: [x86_64-unknown-linux-musl, i686-unknown-linux-musl]
+        include:
+          - target: i686-unknown-linux-gnu
+            packages: libc6-dev-i386 lib32gcc-11-dev
+          - target: x86_64-unknown-linux-gnux32
+            packages: libc6-dev-x32 libx32gcc-11-dev
+            # TODO: Find a Linux image/runner with CONFIG_X86_X32_ABI set
+            cargo_test_opts: --no-run
     steps:
       - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: ${{ matrix.target }}
-      - name: Install multilib
-        run: sudo apt-get update && sudo apt-get install gcc-multilib
+      - name: Install libc and libgcc
+        if: matrix.packages
+        run: |
+          sudo apt-get update
+          sudo apt-get install --no-install-recommends ${{ matrix.packages }}
       - uses: Swatinem/rust-cache@v2
-      - run: cargo test --target=${{ matrix.target }} --features=std
+      - run: cargo test ${{ matrix.cargo_test_opts }} --target=${{ matrix.target }} --features=std
 
   ios-tests:
     name: iOS Simulator Test