Add generate_linkmap feature to Apple CROSSTOOL.
Add generate_linkmap feature to Apple CROSSTOOL.

This adds `generate_linkmap` feature to Apple CROSSTOOL. To generate a
link map, add the `--objc_generate_linkmap` flag to a `bazel build`. By
default, only the top level linkmap file is built. If you want the
linkmap file of the top level target dependencies, add the
`--output_groups=+linkmaps` flag.

Fixes https://github.com/bazelbuild/bazel/issues/9153.

Closes #12016.

PiperOrigin-RevId: 330049354

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