Detect ar executable on Linux.
Detect ar executable on Linux.

This commit makes it possible for the default linux toolchain to detect the ar executable.
This is necessary for rules_foreign_cc as some of their rules depend on ar.

Tested: Manually

Closes #12541.

PiperOrigin-RevId: 351577805

bazelbuild/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,perezd/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,meteorcloudy/bazel,perezd/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,perezd/bazel,katre/bazel,katre/bazel,cushon/bazel,katre/bazel,meteorcloudy/bazel,meteorcloudy/bazel,katre/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,twitter-forks/bazel,bazelbuild/bazel,twitter-forks/bazel,perezd/bazel,katre/bazel,perezd/bazel,cushon/bazel,twitter-forks/bazel,perezd/bazel,bazelbuild/bazel,meteorcloudy/bazel,meteorcloudy/bazel,cushon/bazel,meteorcloudy/bazel,cushon/bazel,cushon/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,cushon/bazel,twitter-forks/bazel,katre/bazel,perezd/bazel,twitter-forks/bazel