Bazel 0.24.0 fails on dynamic_runtime_libs coming from toolchain

[or-shachar]

Relates to #6968

Description of the problem / feature request:

My builds ran fine on bazel 0.23.X.

I tried to use bazel 0.24.0rc7 on one of our repo that is used --crosstool_top=@bazel_toolchains//configs/ubuntu16_04_clang/1.1/bazel_0.20.0/default:toolchain and --extra_toolchains=@bazel_toolchains//configs/ubuntu16_04_clang/1.1/bazel_0.20.0/cpp:cc-toolchain-clang-x86_64-default from bazel toolchain commit bazelbuild/bazel-toolchains@31b5dc8

I got this error:

12:07:26  ERROR: /home/builduser/.cache/bazel/_bazel_builduser/d95f300509f1e228190b211abeba17c4/external/bazel_toolchains/configs/ubuntu16_04_clang/1.1/bazel_0.20.0/default/BUILD:57:1: @bazel_toolchains//configs/ubuntu16_04_clang/1.1/bazel_0.20.0/default:cc-compiler-k8: no such attribute 'dynamic_runtime_libs' in 'cc_toolchain' rule

I didn't see anything in documents of this release about deprecating dynamic_runtime_libs. It may be just a missing documentation.

What operating system are you running Bazel on?

Linux

What's the output of bazel info release?

Bazel 0.24.0rc7

Have you found anything relevant by searching the web?

Didn't see anything interesting .. Other than a note for bazel 0.22.0 that dynamic_runtime_libs is optional.

====
Note: Changing the toolchain and crosstool to point to /bazel_toolchains/configs/ubuntu16_04_clang/1.1/bazel_0.22.0/* solved the issue because there the attribute dynamic_runtime_libs does not exist.
Still I think something needs to be documented about it.

[or-shachar]

@katre - not sure how to provide steps to reproduce as we're running our builds with Remote Execution service I can share our .bazelrc if that's helpful or you can take some repo like rules_scala and try to play with it's bazelrc

[hlopko]

This was guarded by #6942. It was announced in https://blog.bazel.build/2019/01/28/bazel-0.22.0.html. 0.24 release notes will have the announcement that this flag has been flipped.

[or-shachar]

Great! thanks!