Default to module support on and disable on 9.2-

Defaulting to module support off meant master would build a binary
that doesn't open up appropriate packages, which is supported
by the last 11 JRuby releases. This change defaults to on so that
the default build will add those flags. It disables module flags
if the JRuby version installing the gem is 9.2.0 or lower.

Author: headius

Makefile

@@ -2,7 +2,7 @@
 PREFIX = notspecified
 BINDIR = $(PREFIX)/bin
 JRUBY_VERSION = notspecified
-JRUBY_MODULE =
+JRUBY_MODULE = 1
 INSTALLDIR = $(PREFIX)/lib/ruby/shared/rubygems/defaults
 INSTALLDIR9000 = $(PREFIX)/lib/ruby/stdlib/rubygems/defaults
 OLDINSTALLDIR = $(PREFIX)/lib/ruby/site_ruby/1.8/rubygems/defaults

extconf.rb

@@ -4,10 +4,9 @@
 mf = mf.gsub(/^JRUBY_VERSION\s*=.*$/, "JRUBY_VERSION = #{JRUBY_VERSION}")
 
 # Launcher will use .module_opts file if present, otherwise hardcoded add-opens for this module.
-# Pre-9.2.1: ALL-UNNAMED because no name was exported
-# 9.2.1 and higher: org.jruby.dist
-if JRUBY_VERSION !~ /(^1)|(^9\.[01])|(^9\.2\.0\.0)/
-  mf = mf.gsub(/^JRUBY_MODULE\s*=.*$/, "JRUBY_MODULE = 1")
+# Module options are only supported on JRuby 9.2.1 or higher.
+if JRUBY_VERSION =~ /(^1)|(^9\.[01])|(^9\.2\.0\.0)/
+  mf = mf.gsub(/^JRUBY_MODULE\s*=.*1$/, "JRUBY_MODULE =")
 end
 puts mf
 File.open('Makefile', 'wb') {|f| f << mf}