ruby-build 20200401

Add definition for JRuby 9.2.11.1

add definition 2.4.10, 2.5.8, 2.6.6, 2.7.1 and ruby 2.4 EOL

JRuby 9.2.11.1 has been released.
https://www.jruby.org/2020/03/25/jruby-9-2-11-1

Add update-mri and update-jruby scripts

This PR adds update-cruby and update-jruby scripts.
They are provided to update MRI and JRuby definition files.

These scripts are based on script/update-truffleruby.
https://github.com/rbenv/ruby-build/blob/v20200224/script/update-truffleruby

Added rbx-4.*

Add definition for JRuby 9.2.11.0

JRuby 9.2.11.0 has been released.
https://www.jruby.org/2020/03/02/jruby-9-2-11-0

Add definition for JRuby 9.2.10.0

JRuby 9.2.10.0 has been released.
https://www.jruby.org/2020/02/18/jruby-9-2-10-0.html

shorter git command chains

Add truffleruby-dev to install the latest TruffleRuby nightly build

* Otherwise, existing files in the prefix could easily conflict and
  potentially cause very hard to debug errors.
* This is particularly important for *-dev builds which might be
  repeatedly installed to the same directory.

* Uses the latest nightly, which is automatically built.

ruby 2.3 EOL

Update so Ruby 1.9.3 thru 2.3, and rbx can be built with OpenSSL 1.0.2u