WIP. Attempt to fix Github Actions issue with GLIBC

GH Actions is repeatedly failing today for reasons I don’t understand.
Re-running the jobs sometimes works, sometimes doesn’t. Hopefully this
stabilizes it.

----
error: failed to run custom build command for `proc-macro2 v1.0.95`
note: To improve backtraces for build dependencies, set the CARGO_PROFILE_TEST_BUILD_OVERRIDE_DEBUG=true environment variable to enable debug information generation.

Caused by:
  process didn't exit successfully: `/home/runner/work/crc-fast-rust/crc-fast-rust/target/debug/build/proc-macro2-566bea0d21b824a5/build-script-build` (exit status: 1)
  --- stderr
  /home/runner/work/crc-fast-rust/crc-fast-rust/target/debug/build/proc-macro2-566bea0d21b824a5/build-script-build: /lib/aarch64-linux-gnu/libc.so.6: version `GLIBC_2.39' not found (required by /home/runner/work/crc-fast-rust/crc-fast-rust/target/debug/build/proc-macro2-566bea0d21b824a5/build-script-build)
warning: build failed, waiting for other jobs to finish...
----

Author: onethumb

.github/workflows/tests.yml

@@ -18,6 +18,20 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4 # not pinning to commit hash since this is a GitHub action, which we trust
+      - name: Install GLIBC for aarch64 Ubuntu 22.04
+        if: ${{ matrix.os == 'ubuntu-22.04-arm' }}
+        run: |
+            sudo apt update
+            sudo apt install -y libc6
+            wget http://ftp.gnu.org/gnu/libc/glibc-2.39.tar.gz
+            tar -xvzf glibc-2.39.tar.gz
+            cd glibc-2.39
+            mkdir build
+            cd build
+            ../configure --prefix=/opt/glibc-2.39
+            make -j$(nproc)
+            sudo make install
+            export LD_LIBRARY_PATH=/opt/glibc-2.39/lib:$LD_LIBRARY_PATH
       - uses: actions-rust-lang/setup-rust-toolchain@9d7e65c320fdb52dcd45ffaa68deb6c02c8754d9 # v1.12.0
         with:
           toolchain: ${{ matrix.rust-toolchain }}