[ruby/io-nonblock] Add TruffleRuby support and add it in CI

* Do not use a C extension on TruffleRuby for these 3 methods.

https://github.com/ruby/io-nonblock/commit/1b8e52abfa

ext/io/nonblock/extconf.rb

@@ -2,6 +2,11 @@
 require 'mkmf'
 target = "io/nonblock"
 
+unless RUBY_ENGINE == 'ruby'
+  File.write("Makefile", dummy_makefile($srcdir).join(""))
+  return
+end
+
 have_func("rb_io_descriptor")
 
 hdr = %w"fcntl.h"