hack/release: Tag before building
hack/release: Tag before building

This gets the correct main.version value.  Before this commit, you
could have:

  $ hack/release.sh v0.4.0
  ...
  + go build -ldflags ' -X main.version=v0.3.0-273-g...' ...
  ...

With this commit, that same invocation will give you:

  + go build -ldflags ' -X main.version=v0.4.0' ...

The bug is from the initial script in 7b023303 (hack/release: Make it
easy to cross-compile release binaries, 2018-10-02, #397).

derekhiggins/installer,derekhiggins/installer