Set `LANG=C.UTF-8` for actions

[fmeum]

RELNOTES[inc]: Bazel now sets LANG=C.UTF-8 for all actions to avoid a fallback to the ASCII charset for locale-sensitive tools due to the absence of any locale variables. To restore the old behavior, pass --action_env=LANG=C or add the line common --action_env=LANG=C to .bazelrc.