Have go_binary emit CcInfo

[steeve]

Now that Bazel 2.2 is the minimum version for rules_go, I was thinking it would be cool for go_library or go_binary to emit CcInfo.

Benefits are:

• go_library/binary can be directly put into the deps of a cc_library
• linkmode could be automatically inferred
• remove legacy .cc target and associated macros targets, so pure rule

I think it would be easier to do it after #2414 lands, however.

[jayconrod]

I would love to get rid of those .cc targets and not have to deal with cc_import.