title: Gem installation ruby-audio failing
body: <p>I have cloned an existing repository and am now running <code>bundle install</code> - for some reason it fails at the ruby-audio gem.</p>
  
  <pre><code>Installing ruby-audio (1.6.1) with native extensions 
  Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
  
  /Users/thisuser/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb 
  checking for sndfile.h in /opt/local/include,/usr/local/include,C:/Program Files (x86)/Mega-Nerd/libsndfile/include,C:/Program Files/Mega-Nerd/libsndfile/include... no
  checking for sf_open() in -lsndfile-1... no
  checking for sf_open() in -lsndfile... no
  *** extconf.rb failed ***
  Could not create Makefile due to some reason, probably lack of
  necessary libraries and/or headers.  Check the mkmf.log file for more
  details.  You may need configuration options.
  
  Provided configuration options:
  --with-opt-dir
  --with-opt-include
  --without-opt-include=${opt-dir}/include
  --with-opt-lib
  --without-opt-lib=${opt-dir}/lib
  --with-make-prog
  --without-make-prog
  --srcdir=.
  --curdir
  --ruby=/Users/thisuser/.rvm/rubies/ruby-1.9.3-p194/bin/ruby
  --with-sndfile-dir
  --without-sndfile-dir
  --with-sndfile-include
  --without-sndfile-include=${sndfile-dir}/include
  --with-sndfile-lib
  --without-sndfile-lib=${sndfile-dir}/lib
  --with-sndfile-1lib
  --without-sndfile-1lib
  --with-sndfilelib
  --without-sndfilelib
  extconf.rb:26:in `&lt;main&gt;':   Can't find libsndfile (http://www.mega-nerd.com/libsndfile/) (RuntimeError)
  
    Try passing --with-sndfile-dir or --with-sndfile-lib and --with-sndfile-include
    options to extconf. If there are spaces in the path on windows, it may not work.
  
  Gem files will remain installed in /Users/thisuser/.bundler/tmp/5253/gems/ruby-audio-1.6.1 for inspection.
  Results logged to /Users/thisuser/.bundler/tmp/5253/gems/ruby-audio-1.6.1/ext/rubyaudio_ext/gem_make.out
  An error occured while installing ruby-audio (1.6.1), and Bundler cannot continue.
  Make sure that `gem install ruby-audio -v '1.6.1'` succeeds before bundling.
  </code></pre>
  
  <p>Honestly, I have no idea whatsoever what to do with this. Googling showed the same error with the mysql gem, and the solutions were mysql specific.</p>
  
  <p>Has anyone ever stumbled upon this? If not, is there a way to tell rails explicitly to ignore that gem? Removing it from the gem file and running <code>bundle install</code> again did not do the trick.</p>
  
  <p>Thanks for any help!</p>
  
  <p><strong>Edit</strong></p>
  
  <p>After running <code>brew install libsndfile</code> I got the following output:</p>
  
  <pre><code>Warning: Your Xcode (4.5.2) is outdated
  Please install Xcode 4.6.
  ==&gt; Downloading http://www.mega-nerd.com/libsndfile/files/libsndfile-1.0.25.tar.gz
  Already downloaded: /Library/Caches/Homebrew/libsndfile-1.0.25.tar.gz
  ==&gt; Patching
  patching file programs/sndfile-play.c
  ==&gt; ./configure --prefix=/usr/local/Cellar/libsndfile/1.0.25
  ==&gt; make install
  make[1]: *** [sndfile-play.o] Error 1
  make[1]: *** Waiting for unfinished jobs....
  brew: superenv removed: -g -O2 -Wall -Wextra -Wdeclaration-after-statement -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wcast-align -Wcast-qual -Wnested-externs -Wbad-function-cast -Wwrite-strings -Wundef
  brew: superenv removed: -g -O2 -Wall -Wextra -Wdeclaration-after-statement -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wcast-align -Wcast-qual -Wnested-externs -Wbad-function-cast -Wwrite-strings -Wundef
  make: *** [install-recursive] Error 1
  Your Xcode and or CLT are mis-configured. Try some or all of the following:
      xcrun --kill-cache
      xcodebuild -license
      sudo xcode-select -switch /path/to/Xcode.app
  </code></pre>
  
  <p>I tried all of the suggested commands - to no avail. What else can I do to solve this?</p>