title: EventMachine : Failed to build gem native extension
body: <p>I'm trying to install eventmachine:</p>
  
  <pre><code>sudo gem install eventmachine
  
  ...
  
  Building native extensions.  This could take a while...
  /Users/kuankuan/.rvm/rubies/ruby-1.9.3-p327/lib/ruby/1.9.1/rubygems/ext/builder.rb:48: warning: Insecure world writable dir /usr/local/bin/g4bin in PATH, mode 040777
  ERROR:  Error installing eventmachine:
      ERROR: Failed to build gem native extension.
  
          /Users/kuankuan/.rvm/rubies/ruby-1.9.3-p327/bin/ruby extconf.rb
  /Users/kuankuan/.rvm/rubies/ruby-1.9.3-p327/lib/ruby/1.9.1/mkmf.rb:1344: warning: Insecure world writable dir /usr/local/bin/g4bin in PATH, mode 040777
  checking for rb_trap_immediate in ruby.h,rubysig.h... no
  checking for rb_thread_blocking_region()... yes
  checking for inotify_init() in sys/inotify.h... no
  checking for __NR_inotify_init in sys/syscall.h... no
  checking for writev() in sys/uio.h... yes
  checking for rb_thread_check_ints()... yes
  checking for rb_time_new()... yes
  checking for sys/event.h... yes
  checking for sys/queue.h... yes
  creating Makefile
  
  make
  compiling binder.cpp
  cc1plus: error: unrecognized command line option "-arch"
  make: *** [binder.o] Error 1
  </code></pre>
  
  <p>Platform: </p>
  
  <pre><code>Mac OSX 10.8.3
  Ruby 1.9.3p327 (2012-11-10) [x86_64-darwin12.2.0]
  </code></pre>
  
  <p><strong>cc --version</strong></p>
  
  <pre><code>Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
  Target: x86_64-apple-darwin12.3.0
  Thread model: posix
  </code></pre>
  
  <p><strong>gcc --version</strong></p>
  
  <pre><code>gcc (MacPorts gcc44 4.4.7_6) 4.4.7
  Copyright (C) 2010 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  </code></pre>
  
  <p><strong>g++ --version</strong></p>
  
  <pre><code>g++ (MacPorts gcc44 4.4.7_6) 4.4.7
  Copyright (C) 2010 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  </code></pre>
  
  <p><strong>Command Line Tools</strong></p>
  
  <p><img src="https://i.stack.imgur.com/VSV6A.jpg" alt="enter image description here"></p>
  
  <p>And, I've tried to change bundle's config:</p>
  
  <pre><code>sudo bundle config build.eventmachine --with-cflags=\"-O2 -pipe -march=native -w\"    
  </code></pre>