The patch for MacRuby. $ /usr/bin/rake extensions EXTS=readline

support-compiling-only-one.patch

diff --git a/rakelib/builder.rake b/rakelib/builder.rake
index 79e3e41..e3f2ecb 100644
--- a/rakelib/builder.rake
+++ b/rakelib/builder.rake
@@ -328,7 +328,8 @@ INSTRUBY_ARGS = "#{SCRIPT_ARGS} --data-mode=0644 --prog-mode=0755 --installed-li
 
 EXTENSIONS = ['ripper', 'digest', 'etc', 'readline', 'libyaml', 'fcntl', 'socket', 'zlib', 'bigdecimal', 'openssl'].sort
 def perform_extensions_target(target)
-  EXTENSIONS.map { |x| File.join('ext', x) }.each do |ext_dir|
+  target_extensions = (ENV['EXTS'] && ENV['EXTS'].split or EXTENSIONS)
+  target_extensions.map { |x| File.join('ext', x) }.each do |ext_dir|
     Dir.glob(File.join(ext_dir, '**/extconf.rb')) do |p|
       dir = File.dirname(p)
       Dir.chdir(dir) do