Add script to conveniently print versions for ruby-builder

versions-strings-for-builder.rb

@@ -0,0 +1,15 @@
+hash = File.read('ruby-builder-versions.js')[/\bversions = {[^}]+}/]
+versions = eval hash
+
+by_minor = versions[:ruby].group_by { |v| v[/^\d\.\d/] }
+
+p by_minor['2.2']
+p by_minor['2.3']
+
+(4..7).each do |minor|
+  p by_minor["2.#{minor}"].map { |v| "ruby-#{v}" }
+end
+
+p (versions[:jruby] - %w[head]).map { |v| "jruby-#{v}" }
+
+p (versions[:truffleruby] - %w[head]).map { |v| "truffleruby-#{v}" }