Provide dynamically linked alpine binary distributions.

My primary use for Alpine is to produce staticly linked linux binaries. But I don't care how GHC itself is linked, as long as it can produce (both C and Hs) static binaries.

E.g. I don't need #23043 to be resolved, which as far as I understand is a hard issue, but apparently building dynamically linked alpine distibution is not impossible (@maerwald comment #23043 (comment 513809)).

I'd welcome the official dynamic alpine bindists.