Cache rule feature lists

[dzbarsky]

Summary

ctx.features and ctx.disabled_features allocate a new list on every access. Cache those lists in cc_binary, cc_library, objc_library, and objc_import, then pass the cached lists through the existing feature-configuration helpers.

This reduces ctx.features accesses from up to five to one for cc_binary/cc_test, from up to four to one for cc_library, and reduces both property accesses from four to one for objc_library and from two to one for objc_import. Optional helper arguments preserve behavior for existing external callers.

Validation

• buildifier -mode=check on all changed Starlark files
• bazel test --jobs=4 --test_output=errors //tests/cc/common:cc_common_tests //tests/cc/common:cc_binary_configured_target_tests //tests/cc/common:cc_objc_library_configured_target_tests

[lilygorsheneva]

I'm interested in how this will affect build metrics, approving.

[dzbarsky]

I'm interested in how this will affect build metrics, approving.

I'm also curious if you can measure such a micro opt but lemme know!