gazelle_binary: add extra _stdlib attr for older rules_go versions (#906)
gazelle_binary: add extra _stdlib attr for older rules_go versions (#906)

Before rules_go v0.23.0, rules were required to have an _stdlib
attribute, which was usually provided via the go_rules wrapper. Now,
that dependency comes from _go_context_data. Adding an extra edge
keeps us compatible with older versions.

Fixes #896
bazelbuild/bazel-gazelle,bazelbuild/bazel-gazelle