This updates the version of rules_go to 0.9.0. The BUILD files changes were
necessary to work around a linking error that happens under 0.9.0.

The fix was based on bazelbuild/buildtools#201, but I don't really know much about the go build chain, so I don't really know what's happening, nor do I know if there's any specific motivation behind structuring the BUILD file the way it was. I'd be happy to file a bug against rules_go if this change seems like it should unnecessary, but I figured I'd put this up in case we're okay with the workaround.

This update also adds these deprecation warnings:

DEBUG: /private/var/tmp/_bazel_snowp/3bae0aee9d5211471587d3b4956c9db7/external/io_bazel_rules_go/go/private/rules/wrappers.bzl:79:5:
DEPRECATED: //vendor/github.com/lyft/protoc-gen-star:go_default_test : the library attribute on go_test is deprecated. Please migrate to embed.