added #empty? to MySql2::Result

[walf443]

result = client.qeury("SELECT 1 FROM mysql2_test")
unless result.empty? # currently it need to write `if result.count > 0`
   # do something with `result`
end

MySql2::Result include Enumerable. If it added #empty? method, I'm happy to write a code with more rubyish style.

[sodabrew]

#empty? Isn’t a usual part of Enumerable though: https://ruby-doc.org/core-2.5.1/Enumerable.html But Array and Hash do have it. So I can see the utility in the convenience method. Let me think a bit before adding this to the api.

[sodabrew]

Accepted for next major.

[walf443]

oh I see. thanks.