Re-enable Bazel Skylib and rules_foreign_cc (#776)
Re-enable Bazel Skylib and rules_foreign_cc (#776)

Both are green with Bazel@HEAD
https://buildkite.com/bazel/bazel-at-head-plus-disabled/builds/253#_
bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration