JRuby 1.7 HEAD, Bundler, C Extension errors

bundler output

Fetching gem metadata from https://rubygems.org/.......
Fetching gem metadata from https://rubygems.org/..
Using rake (0.9.2.2) 
Installing multi_json (1.1.0) 
Installing activesupport (3.1.4) 
Installing builder (3.0.0) 
Installing i18n (0.6.0) 
Installing activemodel (3.1.4) 
Installing erubis (2.7.0) 
Installing rack (1.3.6) 
Installing rack-cache (1.2) 
Installing rack-mount (0.8.3) 
Installing rack-test (0.6.1) 
Installing hike (1.2.1) 
Installing tilt (1.3.3) 
Installing sprockets (2.0.3) 
Installing actionpack (3.1.4) 
Installing mime-types (1.17.2) 
Installing polyglot (0.3.3) 
Installing treetop (1.4.10) 
Installing mail (2.3.3) 
Installing actionmailer (3.1.4) 
Installing arel (2.2.3) 
Installing tzinfo (0.3.32) 
Installing activerecord (3.1.4) 
Installing activerecord-jdbc-adapter (1.2.2) 
Installing jdbc-sqlite3 (3.7.2) 
Installing activerecord-jdbcsqlite3-adapter (1.2.2) 
Installing activeresource (3.1.4) 
Installing ansi (1.4.2) 
Installing bcrypt-ruby (3.0.1) 
Using bouncy-castle-java (1.5.0146.1) 
Installing bson (1.6.1) 
Using bundler (1.1.1) 
Installing nokogiri (1.5.2) 
Installing ffi (1.0.11) 
Installing childprocess (0.3.1) 
Installing rubyzip (0.9.6.1) 
Installing selenium-webdriver (2.20.0) 
Installing xpath (0.1.4) 
Installing capybara (1.1.2) 
Installing minitest (2.11.3) 
Installing capybara_minitest_spec (0.2.1.1) 
Installing carrierwave (0.5.8) 
Installing mongo (1.6.1) 
Installing mongoid (2.4.6) 
Installing carrierwave-mongoid (0.1.3) 
Installing closure-compiler (1.1.6) 
Installing coderay (1.0.5) 
Installing coffee-script-source (1.2.0) 
Installing execjs (1.3.0) 
Installing coffee-script (2.2.0) 
Installing rack-ssl (1.3.2) 
Installing json (1.6.5) 
Installing rdoc (3.12) 
Installing thor (0.14.6) 
Installing railties (3.1.4) 
Installing coffee-rails (3.1.1) 
Installing database_cleaner (0.7.1) 
Installing orm_adapter (0.0.6) 
Installing warden (1.1.1) 
Installing devise (2.0.4) 
Installing ejs (1.0.0) 
Using event-calendar (2.3.3) from https://github.com/elevation/event_calendar.git (at master) 
Installing factory_girl (2.6.3) 
Installing factory_girl_rails (1.7.0) 
Installing ffaker (1.13.0) 
Installing ffi-locale (1.0.1) 
Installing ffi-ncurses (0.4.0) 
Installing geokit (1.6.5) 
Installing guard (1.0.1) 
Installing guard-bundler (0.1.3) 
Installing guard-minitest (0.5.0) 
Installing has_scope (0.5.1) 
Installing responders (0.8.0) 
Installing inherited_resources (1.3.1) 
Installing jquery-rails (1.0.19) 
Using jruby-openssl (0.7.6.1) 
Installing method_source (0.7.1) 
Installing posix-spawn (0.3.6) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /Users/tsingh/.rvm/rubies/jruby-head/bin/jruby extconf.rb 
WARNING: JRuby does not support native extensions or the `mkmf' library very well.
Check https://wiki.jruby.org/C-Extension-Alternatives for alternatives.
/Users/tsingh/.rvm/rubies/jruby-head/lib/ruby/shared/mkmf.rb:36: Use RbConfig instead of obsolete and deprecated Config.
creating Makefile

make
cc -I. -I/Users/tsingh/.rvm/rubies/jruby-head/lib/native/include -I/Users/tsingh/.rvm/rubies/jruby-head/lib/native/include/ruby -I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE      -fPIC -DTARGET_RT_MAC_CFM=0  -fno-omit-frame-pointer -fno-strict-aliasing  -fexceptions   -Wall   -arch amd64 -c posix-spawn.c
llvm-gcc-4.2: Invalid arch name : amd64
make: *** [posix-spawn.o] Error 1


Gem files will remain installed in /Users/tsingh/.rvm/gems/jruby-head/gems/posix-spawn-0.3.6 for inspection.
Results logged to /Users/tsingh/.rvm/gems/jruby-head/gems/posix-spawn-0.3.6/ext/gem_make.out
An error occured while installing posix-spawn (0.3.6), and Bundler cannot continue.
Make sure that `gem install posix-spawn -v '0.3.6'` succeeds before bundling.

Gemfile

source "https://rubygems.org"

gem "rails", "3.1.4"

gem "jquery-rails"

gem "devise"
gem "inherited_resources"
gem "geokit"

gem "redis"
gem "mongoid"
gem "mongoid_nested_set"
gem "mongoid_slug", require: "mongoid/slug"

gem "carrierwave"
gem "mini_magick"
gem "carrierwave-mongoid", require: "carrierwave/mongoid"
# need the following changes to subexec for mini_magick/subexec to work with jruby 1.9
gem "subexec", git: "https://github.com/astjohn/subexec.git",
               ref: "ec83f69078949e6d21caaffb32e927b971348e12"

gem "event-calendar", require: "event_calendar", git: "https://github.com/elevation/event_calendar.git"
gem "rails-backbone", git: "https://github.com/zenapsis/backbone-rails.git"

gem "mustache"
gem "mustache_rails3", git: "https://github.com/parallel588/mustache_rails3.git"

gem "sprockets"

platforms :jruby do
  gem "jdbc-sqlite3"
  gem "activerecord-jdbc-adapter"
  gem "activerecord-jdbcsqlite3-adapter"

  gem "jruby-openssl"
  gem "ffi-ncurses"
  gem "therubyrhino"
end

platforms :ruby do
  gem "sqlite3"
end

group :assets do
  gem "sass-rails"
  gem "coffee-rails"
  gem "closure-compiler"
end

group :development, :test do
  gem "pry-rails"
  gem "pry-nav"

  gem "guard-minitest"
  gem "guard-bundler"
end

group :test do
  gem "minitest"
  gem "minitest-predicates"
  gem "minitest-mongoid", git: "https://github.com/bemurphy/minitest-mongoid.git"

  gem "capybara"
  gem "capybara_minitest_spec"
  #gem "poltergeist"

  gem "factory_girl_rails"
  gem "ffaker"

  gem "database_cleaner"

  gem "turn"
end